TemplateManualDirective

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TemplateManualDirective Ref for the template commands

man Template::Manual::Directives


NAME
       Template::Manual::Directives - Template directives

Accessing and Updating Template Variables
   GET
       The "GET" directive retrieves and outputs the value of the named
       variable.

           [% GET foo %]

       The "GET" keyword is optional.  A variable can be specified in a
       directive tag by itself.

           [% foo %]

       The variable can have an unlimited number of elements, each separated
       by a dot. Each element can have arguments specified within parentheses.

           [% foo %]
           [% bar.baz %]
           [% biz.baz(10) %]
           ...etc...

       See Template::Manual::Variables for a full discussion on template
       variables.

       You can also specify expressions using the logical ("and", "or", "not",
       "?", ":") and mathematic operators ("+", "-", "*", "/", "%", "mod",
       "div").

           [% template.title or default.title %]

           [% score * 100 %]

           [% order.nitems ? checkout(order.total) : 'no items' %]

       The "div" operator returns the integer result of division.  Both "%"
       and "mod" return the modulus (i.e. remainder) of division.

           [% 15 / 6 %]            # 2.5
           [% 15 div 6 %]          # 2
           [% 15 mod 6 %]          # 3

   CALL
       The "CALL" directive is similar to "GET" in evaluating the variable
       named, but doesn’t print the result returned.  This can be useful when
       a variable is bound to a sub-routine or object method which you want to
       call but aren’t interested in the value returned.

           [% CALL dbi.disconnect %]

           [% CALL inc_page_counter(page_count) %]

   SET
       The "SET" directive allows you to assign new values to existing
       variables or create new temporary variables.

           [% SET title = 'Hello World' %]

       The "SET" keyword is also optional.

           [% title = 'Hello World' %]

       Variables may be assigned the values of other variables, unquoted
       numbers (2.718), literal text (’single quotes’) or quoted text ("double
       quotes").  In the latter case, any variable references within the text
       will be interpolated when the string is evaluated.  Variables should be
       prefixed by "$", using curly braces to explicitly scope the variable
       name where necessary.

           [% foo  = 'Foo'  %]               # literal value 'Foo'
           [% bar  =  foo   %]               # value of variable 'foo'
           [% cost = '$100' %]               # literal value '$100'
           [% item = "$bar: ${cost}.00" %]   # value "Foo: $100.00"

       Multiple variables may be assigned in the same directive and are
       evaluated in the order specified.  Thus, the above could have been
       written:

           [% foo  = 'Foo'
              bar  = foo
              cost = '$100'
              item = "$bar: ${cost}.00"
           %]

       Simple expressions can also be used, as per "GET".

           [% ten    = 10
              twenty = 20
              thirty = twenty + ten
              forty  = 2 * twenty
              fifty  = 100 div 2
              six    = twenty mod 7
           %]

       You can concatenate strings together using the ' _ ' operator.  In Perl
       5, the "." is used for string concatenation, but in Perl 6, as in the
       Template Toolkit, the "." will be used as the method calling operator
       and ' _ ' will be used for string concatenation.  Note that the
       operator must be specified with surrounding whitespace which, as Larry
       says, is construed as a feature:

           [% copyright = '(C) Copyright' _ year _ ' ' _ author %]

       You can, of course, achieve a similar effect with double quoted string
       interpolation.

           [% copyright = "(C) Copyright $year $author" %]

   DEFAULT
       The "DEFAULT" directive is similar to "SET" but only updates variables
       that are currently undefined or have no "true" value (in the Perl
       sense).

           [% DEFAULT
               name = 'John Doe'
               id   = 'jdoe'
           %]

       This can be particularly useful in common template components to ensure
       that some sensible default are provided for otherwise undefined
       variables.

           [% DEFAULT
              title = 'Hello World'
              bgcol = '#ffffff'
           %]
           <html>
             <head>
               <title>[% title %]</title>
             </head>
             <body bgcolor="[% bgcol %]">
               ...etc...

Processing Template Files and Blocks
   INSERT
       The "INSERT" directive is used to insert the contents of an external
       file at the current position.

           [% INSERT myfile %]

       No attempt to parse or process the file is made.  The contents,
       possibly including any embedded template directives, are inserted
       intact.

       The filename specified should be relative to one of the "INCLUDE_PATH"
       directories.  Absolute (i.e. starting with "/") and relative (i.e.
       starting with ".") filenames may be used if the "ABSOLUTE" and
       "RELATIVE" options are set, respectively.  Both these options are
       disabled by default.

           my $template = Template->new({
               INCLUDE_PATH => '/here:/there',
           });

           $template->process('myfile');

       myfile:

           [% INSERT foo %]            # looks for /here/foo then /there/foo
           [% INSERT /etc/passwd %]    # file error: ABSOLUTE not set
           [% INSERT ../secret %]      # file error: RELATIVE not set

       For convenience, the filename does not need to be quoted as long as it
       contains only alphanumeric characters, underscores, dots or forward
       slashes.  Names containing any other characters should be quoted.

           [% INSERT misc/legalese.txt            %]
           [% INSERT 'dos98/Program Files/stupid' %]

       To evaluate a variable to specify a filename, you should explicitly
       prefix it with a "$" or use double-quoted string interpolation.

           [% language = 'en'
              legalese = 'misc/legalese.txt'
           %]

           [% INSERT $legalese %]              # misc/legalese.txt
           [% INSERT "$language/$legalese" %]  # en/misc/legalese.txt

       Multiple files can be specified using "+" as a delimiter.  All files
       should be unquoted names or quoted strings.  Any variables should be
       interpolated into double-quoted strings.

           [% INSERT legalese.txt + warning.txt %]
           [% INSERT  "$legalese" + warning.txt %]  # requires quoting

   INCLUDE
       The "INCLUDE" directive is used to process and include the output of
       another template file or block.

           [% INCLUDE header %]

       If a "BLOCK" of the specified name is defined in the same file, or in a
       file from which the current template has been called (i.e. a parent
       template) then it will be used in preference to any file of the same
       name.

           [% INCLUDE table %]     # uses BLOCK defined below

           [% BLOCK table %]
              <table>
                ...
              </table>
           [% END %]

       If a "BLOCK" definition is not currently visible then the template name
       should be a file relative to one of the "INCLUDE_PATH" directories, or
       an absolute or relative file name if the "ABSOLUTE"/"RELATIVE" options
       are appropriately enabled.  The "INCLUDE" directive automatically
       quotes the filename specified, as per "INSERT" described above.  When a
       variable contains the name of the template for the "INCLUDE" directive,
       it should be explicitly prefixed by "$" or double-quoted

           [% myheader = 'my/misc/header' %]
           [% INCLUDE   myheader  %]           # 'myheader'
           [% INCLUDE  $myheader  %]           # 'my/misc/header'
           [% INCLUDE "$myheader" %]           # 'my/misc/header'

       Any template directives embedded within the file will be processed
       accordingly.  All variables currently defined will be visible and
       accessible from within the included template.

           [% title = 'Hello World' %]
           [% INCLUDE header %]
           <body>
           ...

       header:

           <html>
           <title>[% title %]</title>

       output:

           <html>
           <title>Hello World</title>
           <body>
           ...

       Local variable definitions may be specified after the template name,
       temporarily masking any existing variables.  Insignificant whitespace
       is ignored within directives so you can add variable definitions on the
       same line, the next line or split across several line with comments
       interspersed, if you prefer.

           [% INCLUDE table %]

           [% INCLUDE table title="Active Projects" %]

           [% INCLUDE table
                title   = "Active Projects"
                bgcolor = "#80ff00"    # chartreuse
                border  = 2
           %]

       The "INCLUDE" directive localises (i.e. copies) all variables before
       processing the template.  Any changes made within the included template
       will not affect variables in the including template.

           [% foo = 10 %]

           foo is originally [% foo %]
           [% INCLUDE bar %]
           foo is still [% foo %]

           [% BLOCK bar %]
              foo was [% foo %]
              [% foo = 20 %]
              foo is now [% foo %]
           [% END %]

       output:

           foo is originally 10
              foo was 10
              foo is now 20
           foo is still 10

       Technical Note: the localisation of the stash (that is, the process by
       which variables are copied before an "INCLUDE" to prevent being
       overwritten) is only skin deep.  The top-level variable namespace
       (hash) is copied, but no attempt is made to perform a deep-copy of
       other structures (hashes, arrays, objects, etc.)  Therefore, a "foo"
       variable referencing a hash will be copied to create a new "foo"
       variable but which points to the same hash array.  Thus, if you update
       compound variables (e.g. "foo.bar") then you will change the original
       copy, regardless of any stash localisation.  If you’re not worried
       about preserving variable values, or you trust the templates you’re
       including then you might prefer to use the "PROCESS" directive which is
       faster by virtue of not performing any localisation.

       You can specify dotted variables as "local" variables to an "INCLUDE"
       directive.  However, be aware that because of the localisation issues
       explained above (if you skipped the previous Technical Note above then
       you might want to go back and read it or skip this section too), the
       variables might not actually be "local". If the first element of the
       variable name already references a hash array then the variable update
       will affect the original variable.

           [% foo = {
                  bar = 'Baz'
              }
           %]

           [% INCLUDE somefile foo.bar='Boz' %]

           [% foo.bar %]           # Boz

       This behaviour can be a little unpredictable (and may well be improved
       upon in a future version).  If you know what you’re doing with it and
       you’re sure that the variables in question are defined (nor not) as you
       expect them to be, then you can rely on this feature to implement some
       powerful "global" data sharing techniques.  Otherwise, you might prefer
       to steer well clear and always pass simple (undotted) variables as
       parameters to "INCLUDE" and other similar directives.

       If you want to process several templates in one go then you can specify
       each of their names (quoted or unquoted names only, no unquoted
       $variables) joined together by "+".  The "INCLUDE" directive will then
       process them in order.

           [% INCLUDE html/header + "site/$header" + site/menu
                title = "My Groovy Web Site"
           %]

       The variable stash is localised once and then the templates specified
       are processed in order, all within that same variable context.  This
       makes it slightly faster than specifying several separate "INCLUDE"
       directives (because you only clone the variable stash once instead of n
       times), but not quite as "safe" because any variable changes in the
       first file will be visible in the second, third and so on.  This might
       be what you want, of course, but then again, it might not.

   PROCESS
       The PROCESS directive is similar to "INCLUDE" but does not perform any
       localisation of variables before processing the template.  Any changes
       made to variables within the included template will be visible in the
       including template.

           [% foo = 10 %]

           foo is [% foo %]
           [% PROCESS bar %]
           foo is [% foo %]

           [% BLOCK bar %]
              [% foo = 20 %]
              changed foo to [% foo %]
           [% END %]

       output:

           foo is 10
              changed foo to 20
           foo is 20

       Parameters may be specified in the "PROCESS" directive, but these too
       will become visible changes to current variable values.

           [% foo = 10 %]
           foo is [% foo %]
           [% PROCESS bar
              foo = 20
           %]
           foo is [% foo %]

           [% BLOCK bar %]
              this is bar, foo is [% foo %]
           [% END %]

       output:

           foo is 10
              this is bar, foo is 20
           foo is 20

       The "PROCESS" directive is slightly faster than "INCLUDE" because it
       avoids the need to localise (i.e. copy) the variable stash before
       processing the template.  As with "INSERT" and "INCLUDE", the first
       parameter does not need to be quoted as long as it contains only
       alphanumeric characters, underscores, periods or forward slashes.  A
       "$" prefix can be used to explicitly indicate a variable which should
       be interpolated to provide the template name:

           [% myheader = 'my/misc/header' %]
           [% PROCESS  myheader %]              # 'myheader'
           [% PROCESS $myheader %]              # 'my/misc/header'

       As with "INCLUDE", multiple templates can be specified, delimited by
       "+", and are processed in order.

           [% PROCESS html/header + my/header %]

   WRAPPER
       It’s not unusual to find yourself adding common headers and footers to
       pages or sub-sections within a page.  Something like this:

           [% INCLUDE section/header
              title = 'Quantum Mechanics'
           %]
              Quantum mechanics is a very interesting subject wish
              should prove easy for the layman to fully comprehend.
           [% INCLUDE section/footer %]

           [% INCLUDE section/header
              title = 'Desktop Nuclear Fusion for under $50'
           %]
              This describes a simple device which generates significant
              sustainable electrical power from common tap water by process
              of nuclear fusion.
           [% INCLUDE section/footer %]

       The individual template components being included might look like
       these:

       section/header:

           <p>
           <h2>[% title %]</h2>

       section/footer:

           </p>

       The "WRAPPER" directive provides a way of simplifying this a little. It
       encloses a block up to a matching "END" directive, which is first
       processed to generate some output. This is then passed to the named
       template file or "BLOCK" as the "content" variable.

           [% WRAPPER section
              title = 'Quantum Mechanics'
           %]
              Quantum mechanics is a very interesting subject wish
              should prove easy for the layman to fully comprehend.
           [% END %]

           [% WRAPPER section
              title = 'Desktop Nuclear Fusion for under $50'
           %]
              This describes a simple device which generates significant
              sustainable electrical power from common tap water by process
              of nuclear fusion.
           [% END %]

       The single ’section’ template can then be defined as:

           <h2>[% title %]</h2>
           <p>
             [% content %]
           </p>

       Like other block directives, it can be used in side-effect notation:

           [% INSERT legalese.txt WRAPPER big_bold_table %]

       It’s also possible to specify multiple templates to a "WRAPPER"
       directive.  The specification order indicates outermost to innermost
       wrapper templates.  For example, given the following template block
       definitions:

           [% BLOCK bold   %]<b>[% content %]</b>[% END %]
           [% BLOCK italic %]<i>[% content %]</i>[% END %]

       the directive

           [% WRAPPER bold+italic %]Hello World[% END %]

       would generate the following output:

           <b><i>Hello World</i></b>

   BLOCK
       The "BLOCK"..."END" construct can be used to define template component
       blocks which can be processed with the "INCLUDE", "PROCESS" and
       "WRAPPER" directives.

           [% BLOCK tabrow %]
           <tr>
             <td>[% name %]<td>
             <td>[% email %]</td>
           </tr>
           [% END %]

           <table>
             [% PROCESS tabrow  name='Fred'  email='fred@nowhere.com' %]
             [% PROCESS tabrow  name='Alan'  email='alan@nowhere.com' %]
           </table>

       A "BLOCK" definition can be used before it is defined, as long as the
       definition resides in the same file.  The block definition itself does
       not generate any output.

           [% PROCESS tmpblk %]

           [% BLOCK tmpblk %] This is OK [% END %]

       You can use an anonymous "BLOCK" to capture the output of a template
       fragment.

           [% julius = BLOCK %]
              And Caesar's spirit, ranging for revenge,
              With Ate by his side come hot from hell,
              Shall in these confines with a monarch's voice
              Cry  'Havoc', and let slip the dogs of war;
              That this foul deed shall smell above the earth
              With carrion men, groaning for burial.
           [% END %]

       Like a named block, it can contain any other template directives which
       are processed when the block is defined.  The output generated by the
       block is then assigned to the variable "julius".

       Anonymous "BLOCK"s can also be used to define block macros.  The
       enclosing block is processed each time the macro is called.

           [% MACRO locate BLOCK %]
              The [% animal %] sat on the [% place %].
           [% END %]

           [% locate(animal='cat', place='mat') %]    # The cat sat on the mat
           [% locate(animal='dog', place='log') %]    # The dog sat on the log

Conditional Processing
   IF / UNLESS / ELSIF / ELSE
       The "IF" and "UNLESS" directives can be used to process or ignore a
       block based on some run-time condition.

           [% IF frames %]
              [% INCLUDE frameset %]
           [% END %]

           [% UNLESS text_mode %]
              [% INCLUDE biglogo %]
           [% END %]

       Multiple conditions may be joined with "ELSIF" and/or "ELSE" blocks.

           [% IF age < 10 %]
              Hello [% name %], does your mother know you're
              using her AOL account?
           [% ELSIF age < 18 %]
              Sorry, you're not old enough to enter
              (and too dumb to lie about your age)
           [% ELSE %]
              Welcome [% name %].
           [% END %]

       The following conditional and boolean operators may be used:

           == != < <= > >= && || ! and or not

       Conditions may be arbitrarily complex and are evaluated with the same
       precedence as in Perl.  Parenthesis may be used to explicitly determine
       evaluation order.

           # ridiculously contrived complex example
           [% IF (name == 'admin' || uid <= 0) && mode == 'debug' %]
              I'm confused.
           [% ELSIF more > less %]
              That's more or less correct.
           [% END %]

       The "and", "or" and "not" operator are provided as aliases for "&&",
       "||" and "!", respectively.  Unlike Perl, which treats "and", "or" and
       "not" as separate, lower-precedence versions of the other operators,
       the Template Toolkit performs a straightforward substitution of "and"
       for "&&", and so on.  That means that "and", "or" and "not" have the
       same operator precedence as "&&", "||" and "!".

   SWITCH / CASE
       The "SWITCH" / "CASE" construct can be used to perform a multi-way
       conditional test.  The "SWITCH" directive expects an expression which
       is first evaluated and then compared against each CASE statement in
       turn.  Each "CASE" directive should contain a single value or a list of
       values which should match.  "CASE" may also be left blank or written as
       "[% CASE DEFAULT %]" to specify a default match.  Only one "CASE"
       matches, there is no drop-through between "CASE" statements.

           [% SWITCH myvar %]
           [%   CASE 'value1' %]
                  ...
           [%   CASE ['value2', 'value3'] %]   # multiple values
                  ...
           [%   CASE myhash.keys %]            # ditto
                  ...
           [%   CASE %]                        # default
                  ...
           [% END %]

Loop Processing
   FOREACH
       The "FOREACH" directive will iterate through the items in a list,
       processing the enclosed block for each one.

           [% foo   = 'Foo'
              items = [ 'one', 'two', 'three' ]
           %]

           Things:
           [% FOREACH thing IN [ foo 'Bar' "$foo Baz" ] %]
              * [% thing %]
           [% END %]

           Items:
           [% FOREACH i IN items %]
              * [% i %]
           [% END %]

           Stuff:
           [% stuff = [ foo "$foo Bar" ] %]
           [% FOREACH s IN stuff %]
              * [% s %]
           [% END %]

       output:

           Things:
             * Foo
             * Bar
             * Foo Baz

           Items:
             * one
             * two
             * three

           Stuff:
             * Foo
             * Foo Bar

       You can use also use "=" instead of "IN" if you prefer.

           [% FOREACH i = items %]

       When the "FOREACH" directive is used without specifying a target
       variable, any iterated values which are hash references will be
       automatically imported.

           [% userlist = [
               { id => 'tom',   name => 'Thomas'  },
               { id => 'dick',  name => 'Richard'  },
               { id => 'larry', name => 'Lawrence' },
              ]
           %]

           [% FOREACH user IN userlist %]
              [% user.id %] [% user.name %]
           [% END %]

       short form:

           [% FOREACH userlist %]
              [% id %] [% name %]
           [% END %]

       Note that this particular usage creates a localised variable context to
       prevent the imported hash keys from overwriting any existing variables.
       The imported definitions and any other variables defined in such a
       "FOREACH" loop will be lost at the end of the loop, when the previous
       context and variable values are restored.

       However, under normal operation, the loop variable remains in scope
       after the "FOREACH" loop has ended (caveat: overwriting any variable
       previously in scope). This is useful as the loop variable is secretly
       an iterator object (see below) and can be used to analyse the last
       entry processed by the loop.

       The "FOREACH" directive can also be used to iterate through the entries
       in a hash array.  Each entry in the hash is returned in sorted order
       (based on the key) as a hash array containing ’key’ and ’value’ items.

           [% users = {
                tom   => 'Thomas',
                dick  => 'Richard',
                larry => 'Lawrence',
              }
           %]

           [% FOREACH u IN users %]
              * [% u.key %] : [% u.value %]
           [% END %]

       Output:

              * dick : Richard
              * larry : Lawrence
              * tom : Thomas

       The "NEXT" directive starts the next iteration in the "FOREACH" loop.

           [% FOREACH user IN userlist %]
              [% NEXT IF user.isguest %]
              Name: [% user.name %]    Email: [% user.email %]
           [% END %]

       The "LAST" directive can be used to prematurely exit the loop.  "BREAK"
       is also provided as an alias for "LAST".

           [% FOREACH match IN results.nsort('score').reverse %]
              [% LAST IF match.score < 50 %]
              [% match.score %] : [% match.url %]
           [% END %]

       The "FOREACH" directive is implemented using the Template::Iterator
       module.  A reference to the iterator object for a "FOREACH" directive
       is implicitly available in the "loop" variable.  The following methods
       can be called on the "loop" iterator.

           size()      number of elements in the list
           max()       index number of last element (size - 1)
           index()     index of current iteration from 0 to max()
           count()     iteration counter from 1 to size() (i.e. index() + 1)
           first()     true if the current iteration is the first
           last()      true if the current iteration is the last
           prev()      return the previous item in the list
           next()      return the next item in the list

       See Template::Iterator for further details.

       Example:

           [% FOREACH item IN [ 'foo', 'bar', 'baz' ] -%]
              [%- "<ul>\n" IF loop.first %]
              <li>[% loop.count %]/[% loop.size %]: [% item %]
              [%- "</ul>\n" IF loop.last %]
           [% END %]

       Output:

           <ul>
           <li>1/3: foo
           <li>2/3: bar
           <li>3/3: baz
           </ul>

       Nested loops will work as expected, with the "loop" variable correctly
       referencing the innermost loop and being restored to any previous value
       (i.e. an outer loop) at the end of the loop.

           [% FOREACH group IN grouplist;
                # loop => group iterator
                "Groups:\n" IF loop.first;

                FOREACH user IN group.userlist;
                   # loop => user iterator
                   "$loop.count: $user.name\n";
                END;

                # loop => group iterator
                "End of Groups\n" IF loop.last;
              END
           %]

       The "iterator" plugin can also be used to explicitly create an iterator
       object.  This can be useful within nested loops where you need to keep
       a reference to the outer iterator within the inner loop.  The iterator
       plugin effectively allows you to create an iterator by a name other
       than "loop".  See Template::Plugin::Iterator for further details.

           [% USE giter = iterator(grouplist) %]

           [% FOREACH group IN giter %]
              [% FOREACH user IN group.userlist %]
                    user #[% loop.count %] in
                    group [% giter.count %] is
                    named [% user.name %]
              [% END %]
           [% END %]

   WHILE
       The "WHILE" directive can be used to repeatedly process a template
       block while a conditional expression evaluates true.  The expression
       may be arbitrarily complex as per "IF" / "UNLESS".

           [% WHILE total < 100 %]
              ...
              [% total = calculate_new_total %]
           [% END %]

       An assignment can be enclosed in parenthesis to evaluate the assigned
       value.

           [% WHILE (user = get_next_user_record) %]
              [% user.name %]
           [% END %]

       The "NEXT" directive can be used to start the next iteration of a
       "WHILE" loop and "BREAK" can be used to exit the loop, both as per
       "FOREACH".

       The Template Toolkit uses a failsafe counter to prevent runaway "WHILE"
       loops which would otherwise never terminate.  If the loop exceeds 1000
       iterations then an "undef" exception will be thrown, reporting the
       error:

           WHILE loop terminated (> 1000 iterations)

       The $Template::Directive::WHILE_MAX variable controls this behaviour
       and can be set to a higher value if necessary.

Filters, Plugins, Macros and Perl
   FILTER
       The "FILTER" directive can be used to post-process the output of a
       block.  A number of standard filters are provided with the Template
       Toolkit.  The "html" filter, for example, escapes the ’<’, ’>’ and ’&’
       characters to prevent them from being interpreted as HTML tags or
       entity reference markers.

           [% FILTER html %]
              HTML text may have < and > characters embedded
              which you want converted to the correct HTML entities.
           [% END %]

       output:

              HTML text may have < and > characters embedded
              which you want converted to the correct HTML entities.

       The "FILTER" directive can also follow various other non-block
       directives.  For example:

           [% INCLUDE mytext FILTER html %]

       The "|" character can also be used as an alias for "FILTER".

           [% INCLUDE mytext | html %]

       Multiple filters can be chained together and will be called in
       sequence.

           [% INCLUDE mytext FILTER html FILTER html_para %]

       or

           [% INCLUDE mytext | html | html_para %]

       Filters come in two flavours, known as ’static’ or ’dynamic’.  A static
       filter is a simple subroutine which accepts a text string as the only
       argument and returns the modified text.  The "html" filter is an
       example of a static filter, implemented as:

           sub html_filter {
               my $text = shift;
               for ($text) {
                   s/&/&/g;
                   s/</</g;
                   s/>/>/g;
               }
               return $text;
           }

       Dynamic filters can accept arguments which are specified when the
       filter is called from a template.  The "repeat" filter is such an
       example, accepting a numerical argument which specifies the number of
       times that the input text should be repeated.

           [% FILTER repeat(3) %]blah [% END %]

       output:

           blah blah blah

       These are implemented as filter ’factories’.  The factory subroutine is
       passed a reference to the current Template::Context object along with
       any additional arguments specified.  It should then return a subroutine
       reference (e.g. a closure) which implements the filter.  The "repeat"
       filter factory is implemented like this:

           sub repeat_filter_factory {
               my ($context, $iter) = @_;
               $iter = 1 unless defined $iter;

               return sub {
                   my $text = shift;
                   $text = '' unless defined $text;
                   return join('\n', $text) x $iter;
               }
           }

       The "FILTERS" option, described in Template::Manual::Config, allows
       custom filters to be defined when a Template object is instantiated.
       The define_filter() method allows further filters to be defined at any
       time.

       When using a filter, it is possible to assign an alias to it for
       further use.  This is most useful for dynamic filters that you want to
       re-use with the same configuration.

           [% FILTER echo = repeat(2) %]
           Is there anybody out there?
           [% END %]

           [% FILTER echo %]
           Mother, should I build a wall?
           [% END %]

       Output:

           Is there anybody out there?
           Is there anybody out there?

           Mother, should I build a wall?
           Mother, should I build a wall?

       The "FILTER" directive automatically quotes the name of the filter.  As
       with "INCLUDE" et al, you can use a variable to provide the name of the
       filter, prefixed by "$".

           [% myfilter = 'html' %]
           [% FILTER $myfilter %]      # same as [% FILTER html %]
              ...
           [% END %]

       A template variable can also be used to define a static filter
       subroutine.  However, the Template Toolkit will automatically call any
       subroutine bound to a variable and use the value returned.  Thus, the
       above example could be implemented as:

           my $vars = {
               myfilter => sub { return 'html' },
           };

       template:

           [% FILTER $myfilter %]      # same as [% FILTER html %]
              ...
           [% END %]

       To define a template variable that evaluates to a subroutine reference
       that can be used by the "FILTER" directive, you should create a
       subroutine that, when called automatically by the Template Toolkit,
       returns another subroutine reference which can then be used to perform
       the filter operation.  Note that only static filters can be implemented
       in this way.

           my $vars = {
               myfilter => sub { \&my_filter_sub },
           };

           sub my_filter_sub {
               my $text = shift;
               # do something
               return $text;
           }

       template:

           [% FILTER $myfilter %]
              ...
           [% END %]

       Alternately, you can bless a subroutine reference into a class (any
       class will do) to fool the Template Toolkit into thinking it’s an
       object rather than a subroutine.  This will then bypass the automatic
       "call-a-subroutine-to-return-a-value" magic.

           my $vars = {
               myfilter => bless(\&my_filter_sub, 'anything_you_like'),
           };

       template:

           [% FILTER $myfilter %]
              ...
           [% END %]

       Filters bound to template variables remain local to the variable
       context in which they are defined. That is, if you define a filter in a
       "PERL" block within a template that is loaded via "INCLUDE", then the
       filter definition will only exist until the end of that template when
       the stash is delocalised, restoring the previous variable state. If you
       want to define a filter which persists for the lifetime of the
       processor, or define additional dynamic filter factories, then you can
       call the define_filter() method on the current Template::Context
       object.

       See Template::Manual::Filters for a complete list of available filters,
       their descriptions and examples of use.

   USE
       The "USE" directive can be used to load and initialise "plugin"
       extension modules.

           [% USE myplugin %]

       A plugin is a regular Perl module that conforms to a particular object-
       oriented interface, allowing it to be loaded into and used
       automatically by the Template Toolkit.  For details of this interface
       and information on writing plugins, consult Template::Plugin.

       A number of standard plugins are included with the Template Toolkit
       (see below and Template::Manual::Plugins).  The names of these standard
       plugins are case insensitive.

           [% USE CGI   %]        # => Template::Plugin::CGI
           [% USE Cgi   %]        # => Template::Plugin::CGI
           [% USE cgi   %]        # => Template::Plugin::CGI

       You can also define further plugins using the "PLUGINS" option.

           my $tt = Template->new({
               PLUGINS => {
                   foo => 'My::Plugin::Foo',
                   bar => 'My::Plugin::Bar',
               },
           });

       The recommended convention is to specify these plugin names in lower
       case.  The Template Toolkit first looks for an exact case-sensitive
       match and then tries the lower case conversion of the name specified.

           [% USE Foo %]      # look for 'Foo' then 'foo'

       If you define all your "PLUGINS" with lower case names then they will
       be located regardless of how the user specifies the name in the "USE"
       directive.  If, on the other hand, you define your "PLUGINS" with upper
       or mixed case names then the name specified in the "USE" directive must
       match the case exactly.

       If the plugin isn’t defined in either the standard plugins
       ($Template::Plugins::STD_PLUGINS) or via the "PLUGINS" option, then the
       "PLUGIN_BASE" is searched.

       In this case the plugin name is case-sensitive.  It is appended to each
       of the "PLUGIN_BASE" module namespaces in turn (default:
       "Template::Plugin") to construct a full module name which it attempts
       to locate and load.  Any periods, ’"."’, in the name will be converted
       to ’"::"’.

           [% USE MyPlugin %]     #  => Template::Plugin::MyPlugin
           [% USE Foo.Bar  %]     #  => Template::Plugin::Foo::Bar

       The "LOAD_PERL" option (disabled by default) provides a further way by
       which external Perl modules may be loaded.  If a regular Perl module
       (i.e. not a "Template::Plugin::*" or other module relative to some
       "PLUGIN_BASE") supports an object-oriented interface and a "new()"
       constructor then it can be loaded and instantiated automatically.  The
       following trivial example shows how the IO::File module might be used.

           [% USE file = IO.File('/tmp/mydata') %]

           [% WHILE (line = file.getline) %]
              <!-- [% line %] -->
           [% END %]

       Any additional parameters supplied in parenthesis after the plugin name
       will be also be passed to the "new()" constructor.  A reference to the
       current Template::Context object is passed as the first parameter.

           [% USE MyPlugin('foo', 123) %]

       equivalent to:

           Template::Plugin::MyPlugin->new($context, 'foo', 123);

       The only exception to this is when a module is loaded via the
       "LOAD_PERL" option.  In this case the $context reference is not passed
       to the "new()" constructor.  This is based on the assumption that the
       module is a regular Perl module rather than a Template Toolkit plugin
       so isn’t expecting a context reference and wouldn’t know what to do
       with it anyway.

       Named parameters may also be specified.  These are collated into a hash
       which is passed by reference as the last parameter to the constructor,
       as per the general code calling interface.

           [% USE url('/cgi-bin/foo', mode='submit', debug=1) %]

       equivalent to:

           Template::Plugin::URL->new(
               $context,
               '/cgi-bin/foo'
               { mode => 'submit', debug => 1 }
           );

       The plugin may represent any data type; a simple variable, hash, list
       or code reference, but in the general case it will be an object
       reference.  Methods can be called on the object (or the relevant
       members of the specific data type) in the usual way:

           [% USE table(mydata, rows=3) %]

           [% FOREACH row IN table.rows %]
              <tr>
              [% FOREACH item IN row %]
               <td>[% item %]</td>
              [% END %]
              </tr>
           [% END %]

       An alternative name may be provided for the plugin by which it can be
       referenced:

           [% USE scores = table(myscores, cols=5) %]

           [% FOREACH row IN scores.rows %]
              ...
           [% END %]

       You can use this approach to create multiple plugin objects with
       different configurations.  This example shows how the format plugin is
       used to create sub-routines bound to variables for formatting text as
       per "printf()".

           [% USE bold = format('<b>%s</b>') %]
           [% USE ital = format('<i>%s</i>') %]
           [% bold('This is bold')   %]
           [% ital('This is italic') %]

       Output:

           <b>This is bold</b>
           <i>This is italic</i>

       This next example shows how the URL plugin can be used to build dynamic
       URLs from a base part and optional query parameters.

           [% USE mycgi = URL('/cgi-bin/foo.pl', debug=1) %]
           <a href="[% mycgi %]">...
           <a href="[% mycgi(mode='submit') %]"...

       Output:

           <a href="/cgi-bin/foo.pl?debug=1">...
           <a href="/cgi-bin/foo.pl?mode=submit&debug=1">...

       The CGI plugin is an example of one which delegates to another Perl
       module. In this case, to Lincoln Stein’s "CGI" module.  All of the
       methods provided by the "CGI" module are available via the plugin.

           [% USE CGI;
              CGI.start_form;
              CGI.checkbox_group( name   = 'colours',
                                  values = [ 'red' 'green' 'blue' ] );
              CGI.popup_menu( name   = 'items',
                              values = [ 'foo' 'bar' 'baz' ] );
              CGI.end_form
           %]

       See Template::Manual::Plugins for more information on the plugins
       distributed with the toolkit or available from CPAN.

   MACRO
       The "MACRO" directive allows you to define a directive or directive
       block which is then evaluated each time the macro is called.

           [% MACRO header INCLUDE header %]

       Calling the macro as:

           [% header %]

       is then equivalent to:

           [% INCLUDE header %]

       Macros can be passed named parameters when called.  These values remain
       local to the macro.

           [% header(title='Hello World') %]

       equivalent to:

           [% INCLUDE header title='Hello World' %]

       A "MACRO" definition may include parameter names.  Values passed to the
       macros are then mapped to these local variables.  Other named
       parameters may follow these.

           [% MACRO header(title) INCLUDE header %]
           [% header('Hello World') %]
           [% header('Hello World', bgcol='#123456') %]

       equivalent to:

           [% INCLUDE header title='Hello World' %]
           [% INCLUDE header title='Hello World' bgcol='#123456' %]

       Here’s another example, defining a macro for display numbers in comma-
       delimited groups of 3, using the chunk and join virtual method.

           [% MACRO number(n) GET n.chunk(-3).join(',') %]
           [% number(1234567) %]    # 1,234,567

       A "MACRO" may precede any directive and must conform to the structure
       of the directive.

           [% MACRO header IF frames %]
              [% INCLUDE frames/header %]
           [% ELSE %]
              [% INCLUDE header %]
           [% END %]

           [% header %]

       A "MACRO" may also be defined as an anonymous "BLOCK".  The block will
       be evaluated each time the macro is called.

           [% MACRO header BLOCK %]
              ...content...
           [% END %]

           [% header %]

       If you’ve got the "EVAL_PERL" option set, then you can even define a
       "MACRO" as a "PERL" block (see below):

           [% MACRO triple(n) PERL %]
                my $n = $stash->get('n');
                print $n * 3;
           [% END -%]

   PERL
       (for the advanced reader)

       The "PERL" directive is used to mark the start of a block which
       contains Perl code for evaluation.  The "EVAL_PERL" option must be
       enabled for Perl code to be evaluated or a "perl" exception will be
       thrown with the message ’"EVAL_PERL not set"’.

       Perl code is evaluated in the "Template::Perl" package.  The $context
       package variable contains a reference to the current Template::Context
       object.  This can be used to access the functionality of the Template
       Toolkit to process other templates, load plugins, filters, etc.  See
       Template::Context for further details.

           [% PERL %]
              print $context->include('myfile');
           [% END %]

       The $stash variable contains a reference to the top-level stash object
       which manages template variables.  Through this, variable values can be
       retrieved and updated.  See Template::Stash for further details.

           [% PERL %]
              $stash->set(foo => 'bar');
              print "foo value: ", $stash->get('foo');
           [% END %]

       Output:

           foo value: bar

       Output is generated from the "PERL" block by calling "print()".  Note
       that the "Template::Perl::PERLOUT" handle is selected (tied to an
       output buffer) instead of "STDOUT".

           [% PERL %]
              print "foo\n";                           # OK
              print PERLOUT "bar\n";                   # OK, same as above
              print Template::Perl::PERLOUT "baz\n";   # OK, same as above
              print STDOUT "qux\n";                    # WRONG!
           [% END %]

       The "PERL" block may contain other template directives.  These are
       processed before the Perl code is evaluated.

           [% name = 'Fred Smith' %]

           [% PERL %]
              print "[% name %]\n";
           [% END %]

       Thus, the Perl code in the above example is evaluated as:

           print "Fred Smith\n";

       Exceptions may be thrown from within "PERL" blocks using "die()".  They
       will be correctly caught by enclosing "TRY" blocks.

           [% TRY %]
              [% PERL %]
                 die "nothing to live for\n";
              [% END %]
           [% CATCH %]
              error: [% error.info %]
           [% END %]

       output:
              error: nothing to live for

   RAWPERL
       (for the very advanced reader)

       The Template Toolkit parser reads a source template and generates the
       text of a Perl subroutine as output.  It then uses "eval()" to evaluate
       it into a subroutine reference.  This subroutine is then called to
       process the template, passing a reference to the current
       Template::Context object through which the functionality of the
       Template Toolkit can be accessed.  The subroutine reference can be
       cached, allowing the template to be processed repeatedly without
       requiring any further parsing.

       For example, a template such as:

           [% PROCESS header %]
           The [% animal %] sat on the [% location %]
           [% PROCESS footer %]

       is converted into the following Perl subroutine definition:

           sub {
               my $context = shift;
               my $stash   = $context->stash;
               my $output  = '';
               my $error;

               eval { BLOCK: {
                   $output .=  $context->process('header');
                   $output .=  "The ";
                   $output .=  $stash->get('animal');
                   $output .=  " sat on the ";
                   $output .=  $stash->get('location');
                   $output .=  $context->process('footer');
                   $output .=  "\n";
               } };
               if ($@) {
                   $error = $context->catch($@, \$output);
                   die $error unless $error->type eq 'return';
               }

               return $output;
           }

       To examine the Perl code generated, such as in the above example, set
       the $Template::Parser::DEBUG package variable to any true value.  You
       can also set the $Template::Directive::PRETTY variable true to have the
       code formatted in a readable manner for human consumption.  The source
       code for each generated template subroutine will be printed to "STDERR"
       on compilation (i.e. the first time a template is used).

           $Template::Parser::DEBUG = 1;
           $Template::Directive::PRETTY = 1;

           $template->process($file, $vars)
               || die $template->error(), "\n";

       The "PERL" ... "END" construct allows Perl code to be embedded into a
       template when the "EVAL_PERL" option is set.  It is evaluated at
       "runtime" using "eval()" each time the template subroutine is called.
       This is inherently flexible, but not as efficient as it could be,
       especially in a persistent server environment where a template may be
       processed many times.

       The "RAWPERL" directive allows you to write Perl code that is
       integrated directly into the generated Perl subroutine text.  It is
       evaluated once at compile time and is stored in cached form as part of
       the compiled template subroutine.  This makes "RAWPERL" blocks more
       efficient than "PERL" blocks.

       The downside is that you must code much closer to the metal. For
       example, in a "PERL" block you can call print() to generate some
       output. "RAWPERL" blocks don’t afford such luxury. The code is inserted
       directly into the generated subroutine text and should conform to the
       convention of appending to the $output variable.

           [% PROCESS  header %]

           [% RAWPERL %]
              $output .= "Some output\n";
              ...
              $output .= "Some more output\n";
           [% END %]

       The critical section of the generated subroutine for this example would
       then look something like:

           ...
           eval { BLOCK: {
               $output .=  $context->process('header');
               $output .=  "\n";
               $output .= "Some output\n";
               ...
               $output .= "Some more output\n";
               $output .=  "\n";
           } };
           ...

       As with "PERL" blocks, the $context and $stash references are pre-
       defined and available for use within "RAWPERL" code.

Exception Handling and Flow Control
   TRY / THROW / CATCH / FINAL
       (more advanced material)

       The Template Toolkit supports fully functional, nested exception
       handling.  The "TRY" directive introduces an exception handling scope
       which continues until the matching "END" directive.  Any errors that
       occur within that block will be caught and can be handled by one of the
       "CATCH" blocks defined.

           [% TRY %]
              ...blah...blah...
              [% CALL somecode %]
              ...etc...
              [% INCLUDE someblock %]
              ...and so on...
           [% CATCH %]
              An error occurred!
           [% END %]

       Errors are raised as exceptions (objects of the Template::Exception
       class) which contain two fields: "type" and "info". The exception
       "type" is used to indicate the kind of error that occurred. It is a
       simple text string which can contain letters, numbers, ’"_"’ or ’"."’.
       The "info" field contains an error message indicating what actually
       went wrong. Within a catch block, the exception object is aliased to
       the "error" variable. You can access the "type" and "info" fields
       directly.

           [% mydsn = 'dbi:MySQL:foobar' %]
           ...

           [% TRY %]
              [% USE DBI(mydsn) %]
           [% CATCH %]
              ERROR! Type: [% error.type %]
                     Info: [% error.info %]
           [% END %]

       output (assuming a non-existent database called ’"foobar"’):

           ERROR!  Type: DBI
                   Info: Unknown database "foobar"

       The "error" variable can also be specified by itself and will return a
       string of the form ""$type error - $info"".

           ...
           [% CATCH %]
           ERROR: [% error %]
           [% END %]

       Output:

           ERROR: DBI error - Unknown database "foobar"

       Each "CATCH" block may be specified with a particular exception type
       denoting the kind of error that it should catch.  Multiple "CATCH"
       blocks can be provided to handle different types of exception that may
       be thrown in the "TRY" block.  A "CATCH" block specified without any
       type, as in the previous example, is a default handler which will catch
       any otherwise uncaught exceptions.  This can also be specified as "[%
       CATCH DEFAULT %]".

           [% TRY %]
              [% INCLUDE myfile %]
              [% USE DBI(mydsn) %]
              [% CALL somecode %]
           [% CATCH file %]
              File Error! [% error.info %]
           [% CATCH DBI %]
              [% INCLUDE database/error.html %]
           [% CATCH %]
              [% error %]
           [% END %]

       Remember that you can specify multiple directives within a single tag,
       each delimited by ’";"’.  So the above example can be written more
       concisely as:

           [% TRY;
                  INCLUDE myfile;
                  USE DBI(mydsn);
                  CALL somecode;
              CATCH file;
                  "File Error! $error.info";
              CATCH DBI;
                  INCLUDE database/error.html;
              CATCH;
                  error;
              END
           %]

       The "DBI" plugin throws exceptions of the "DBI" type (in case that
       wasn’t already obvious).  The other specific exception caught here is
       of the "file" type.

       A "file" exception is automatically thrown by the Template Toolkit when
       it can’t find a file, or fails to load, parse or process a file that
       has been requested by an "INCLUDE", "PROCESS", "INSERT" or "WRAPPER"
       directive.  If "myfile" can’t be found in the example above, the "[%
       INCLUDE myfile %]" directive will raise a "file" exception which is
       then caught by the "[% CATCH file %]" block.  The output generated
       would be:

           File Error! myfile: not found

       Note that the "DEFAULT" option (disabled by default) allows you to
       specify a default file to be used any time a template file can’t be
       found. This will prevent file exceptions from ever being raised when a
       non-existent file is requested (unless, of course, the "DEFAULT" file
       your specify doesn’t exist).  Errors encountered once the file has been
       found (i.e. read error, parse error) will be raised as file exceptions
       as per usual.

       Uncaught exceptions (i.e. if the "TRY" block doesn’t have a type
       specific or default "CATCH" handler) may be caught by enclosing "TRY"
       blocks which can be nested indefinitely across multiple templates. If
       the error isn’t caught at any level then processing will stop and the
       Template process() method will return a false value to the caller. The
       relevant Template::Exception object can be retrieved by calling the
       error() method.

           [% TRY %]
              ...
              [% TRY %]
                 [% INCLUDE $user.header %]
              [% CATCH file %]
                 [% INCLUDE header %]
              [% END %]
              ...
           [% CATCH DBI %]
              [% INCLUDE database/error.html %]
           [% END %]

       In this example, the inner "TRY" block is used to ensure that the first
       "INCLUDE" directive works as expected.  We’re using a variable to
       provide the name of the template we want to include, "user.header", and
       it’s possible this contains the name of a non-existent template, or
       perhaps one containing invalid template directives.  If the "INCLUDE"
       fails with a "file" error then we "CATCH" it in the inner block and
       "INCLUDE" the default "header" file instead.  Any "DBI" errors that
       occur within the scope of the outer "TRY" block will be caught in the
       relevant "CATCH" block, causing the "database/error.html" template to
       be processed.  Note that included templates inherit all currently
       defined template variable so these error files can quite happily access
       the <error> variable to retrieve information about the currently caught
       exception.  For example, the "database/error.html" template might look
       like this:

           <h2>Database Error</h2>
           A database error has occurred: [% error.info %]

       You can also specify a "FINAL" block.  This is always processed
       regardless of the outcome of the "TRY" and/or "CATCH" blocks.  If an
       exception is uncaught then the "FINAL" block is processed before
       jumping to the enclosing block or returning to the caller.

           [% TRY %]
              ...
           [% CATCH this %]
              ...
           [% CATCH that %]
              ...
           [% FINAL %]
              All done!
           [% END %]

       The output from the "TRY" block is left intact up to the point where an
       exception occurs.  For example, this template:

           [% TRY %]
              This gets printed
              [% THROW food 'carrots' %]
              This doesn't
           [% CATCH food %]
              culinary delights: [% error.info %]
           [% END %]

       generates the following output:

           This gets printed
           culinary delights: carrots

       The "CLEAR" directive can be used in a "CATCH" or "FINAL" block to
       clear any output created in the "TRY" block.

           [% TRY %]
              This gets printed
              [% THROW food 'carrots' %]
              This doesn't
           [% CATCH food %]
              [% CLEAR %]
              culinary delights: [% error.info %]
           [% END %]

       Output:

           culinary delights: carrots

       Exception types are hierarchical, with each level being separated by
       the familiar dot operator.  A "DBI.connect" exception is a more
       specific kind of "DBI" error.  Similarly, an "example.error.barf" is a
       more specific kind of "example.error" type which itself is also a
       "example" error.

       A "CATCH" handler that specifies a general exception type (such as
       "DBI" or "example.error") will also catch more specific types that have
       the same prefix as long as a more specific handler isn’t defined.  Note
       that the order in which "CATCH" handlers are defined is irrelevant; a
       more specific handler will always catch an exception in preference to a
       more generic or default one.

           [% TRY %]
              ...
           [% CATCH DBI ;
                INCLUDE database/error.html ;
              CATCH DBI.connect ;
                INCLUDE database/connect.html ;
              CATCH ;
                INCLUDE error.html ;
              END
           %]

       In this example, a "DBI.connect" error has it’s own handler, a more
       general "DBI" block is used for all other "DBI" or "DBI.*" errors and a
       default handler catches everything else.

       Exceptions can be raised in a template using the "THROW" directive.
       The first parameter is the exception type which doesn’t need to be
       quoted (but can be, it’s the same as "INCLUDE") followed by the
       relevant error message which can be any regular value such as a quoted
       string, variable, etc.

           [% THROW food "Missing ingredients: $recipe.error" %]
           [% THROW user.login 'no user id: please login' %]
           [% THROW $myerror.type "My Error: $myerror.info" %]

       It’s also possible to specify additional positional or named parameters
       to the "THROW" directive if you want to pass more than just a simple
       message back as the error info field.

           [% THROW food 'eggs' 'flour' msg='Missing Ingredients' %]

       In this case, the error "info" field will be a hash array containing
       the named arguments and an "args" item which contains a list of the
       positional arguments.

           type => 'food',
           info => {
               msg  => 'Missing Ingredients',
               args => ['eggs', 'flour'],
           }

       In addition to specifying individual positional arguments as "[%
       error.info.args.n %]", the "info" hash contains keys directly pointing
       to the positional arguments, as a convenient shortcut.

           [% error.info.0 %]   # same as [% error.info.args.0 %]

       Exceptions can also be thrown from Perl code which you’ve bound to
       template variables, or defined as a plugin or other extension.  To
       raise an exception, call "die()" passing a reference to a
       Template::Exception object as the argument.  This will then be caught
       by any enclosing "TRY" blocks from where the code was called.

           use Template::Exception;
           ...
           my $vars = {
               foo => sub {
                   # ... do something ...
                   die Template::Exception->new('myerr.naughty',
                                                'Bad, bad error');
               },
           };

       Template:

           [% TRY %]
              [% foo %]
           [% CATCH myerr ;
                "Error: $error" ;
              END
           %]

       Output:

           Error: myerr.naughty error - Bad, bad error

       The "info" field can also be a reference to another object or data
       structure, if required.

           die Template::Exception->new('myerror', {
               module => 'foo.pl',
               errors => [ 'bad permissions', 'naughty boy' ],
           });

       Later, in a template:

           [% TRY %]
              ...
           [% CATCH myerror %]
              [% error.info.errors.size or 'no';
                 error.info.errors.size == 1 ? ' error' : ' errors' %]
              in [% error.info.module %]:
                 [% error.info.errors.join(', ') %].
           [% END %]

       Generating the output:

              2 errors in foo.pl:
                 bad permissions, naughty boy.

       You can also call "die()" with a single string, as is common in much
       existing Perl code.  This will automatically be converted to an
       exception of the ’"undef"’ type (that’s the literal string ’"undef"’,
       not the undefined value).  If the string isn’t terminated with a
       newline then Perl will append the familiar " at $file line $line"
       message.

           sub foo {
               # ... do something ...
               die "I'm sorry, Dave, I can't do that\n";
           }

       If you’re writing a plugin, or some extension code that has the current
       Template::Context in scope (you can safely skip this section if this
       means nothing to you) then you can also raise an exception by calling
       the context throw() method. You can pass it an Template::Exception
       object reference, a pair of "($type, $info)" parameters or just an
       $info string to create an exception of ’"undef"’ type.

           $context->throw($e);            # exception object
           $context->throw('Denied');      # 'undef' type
           $context->throw('user.passwd', 'Bad Password');

   NEXT
       The "NEXT" directive can be used to start the next iteration of a
       "FOREACH" or "WHILE" loop.

           [% FOREACH user IN users %]
              [% NEXT IF user.isguest %]
              Name: [% user.name %]    Email: [% user.email %]
           [% END %]

   LAST
       The "LAST" directive can be used to prematurely exit a "FOREACH" or
       "WHILE" loop.

           [% FOREACH user IN users %]
              Name: [% user.name %]    Email: [% user.email %]
              [% LAST IF some.condition %]
           [% END %]

       "BREAK" can also be used as an alias for "LAST".

   RETURN
       The "RETURN" directive can be used to stop processing the current
       template and return to the template from which it was called, resuming
       processing at the point immediately after the "INCLUDE", "PROCESS" or
       "WRAPPER" directive. If there is no enclosing template then the
       Template process() method will return to the calling code with a true
       value.

           Before
           [% INCLUDE half_wit %]
           After

           [% BLOCK half_wit %]
           This is just half...
           [% RETURN %]
           ...a complete block
           [% END %]

       Output:

           Before
           This is just half...
           After

   STOP
       The "STOP" directive can be used to indicate that the processor should
       stop gracefully without processing any more of the template document.
       This is a planned stop and the Template process() method will return a
       true value to the caller. This indicates that the template was
       processed successfully according to the directives within it.

           [% IF something.terrible.happened %]
              [% INCLUDE fatal/error.html %]
              [% STOP %]
           [% END %]

           [% TRY %]
              [% USE DBI(mydsn) %]
              ...
           [% CATCH DBI.connect %]
              <h1>Cannot connect to the database: [% error.info %]</h1>
              <p>
                We apologise for the inconvenience.
              </p>
              [% INCLUDE footer %]
              [% STOP %]
           [% END %]

   CLEAR
       The "CLEAR" directive can be used to clear the output buffer for the
       current enclosing block.   It is most commonly used to clear the output
       generated from a "TRY" block up to the point where the error occurred.

           [% TRY %]
              blah blah blah            # this is normally left intact
              [% THROW some 'error' %]  # up to the point of error
              ...
           [% CATCH %]
              [% CLEAR %]               # clear the TRY output
              [% error %]               # print error string
           [% END %]

Miscellaneous
   META
       The "META" directive allows simple metadata items to be defined within
       a template. These are evaluated when the template is parsed and as such
       may only contain simple values (e.g. it’s not possible to interpolate
       other variables values into "META" variables).

           [% META
              title   = 'The Cat in the Hat'
              author  = 'Dr. Seuss'
              version = 1.23
           %]

       The "template" variable contains a reference to the main template being
       processed.  These metadata items may be retrieved as attributes of the
       template.

           <h1>[% template.title %]</h1>
           <h2>[% template.author %]</h2>

       The "name" and "modtime" metadata items are automatically defined for
       each template to contain its name and modification time in seconds
       since the epoch.

           [% USE date %]              # use Date plugin to format time
           ...
           [% template.name %] last modified
           at [% date.format(template.modtime) %]

       The "PRE_PROCESS" and "POST_PROCESS" options allow common headers and
       footers to be added to all templates.  The "template" reference is
       correctly defined when these templates are processed, allowing headers
       and footers to reference metadata items from the main template.

           $template = Template->new({
               PRE_PROCESS  => 'header',
               POST_PROCESS => 'footer',
           });

           $template->process('cat_in_hat');

       header:

           <html>
             <head>
               <title>[% template.title %]</title>
             </head>
             <body>

       cat_in_hat:

           [% META
                title   = 'The Cat in the Hat'
                author  = 'Dr. Seuss'
                version = 1.23
                year    = 2000
           %]

               The cat in the hat sat on the mat.

       footer:

               <hr>
               © [% template.year %] [% template.author %]
             </body>
           </html>

       The output generated from the above example is:

           <html>
             <head>
               <title>The Cat in the Hat</title>
             </head>
             <body>
               The cat in the hat sat on the mat.
               <hr>
               © 2000 Dr. Seuss
             </body>
           </html>

   TAGS
       The "TAGS" directive can be used to set the "START_TAG" and "END_TAG"
       values on a per-template file basis.

           [% TAGS <+ +> %]

           <+ INCLUDE header +>

       The TAGS directive may also be used to set a named "TAG_STYLE"

           [% TAGS html %]
           <!-- INCLUDE header -->

       See the TAGS and TAG_STYLE configuration options for further details.

   DEBUG
       The "DEBUG" directive can be used to enable or disable directive debug
       messages within a template.  The "DEBUG" configuration option must be
       set to include "DEBUG_DIRS" for the "DEBUG" directives to have any
       effect.  If "DEBUG_DIRS" is not set then the parser will automatically
       ignore and remove any "DEBUG" directives.

       The "DEBUG" directive can be used with an "on" or "off" parameter to
       enable or disable directive debugging messages from that point forward.
       When enabled, the output of each directive in the generated output will
       be prefixed by a comment indicate the file, line and original directive
       text.

           [% DEBUG on %]
           directive debugging is on (assuming DEBUG option is set true)
           [% DEBUG off %]
           directive debugging is off

       The "format" parameter can be used to change the format of the
       debugging message.

           [% DEBUG format '<!-- $file line $line : [% $text %] -->' %]



perl v5.10.1                      2013-07-23   Template::Manual::Directives(3)