Provided by: libtemplate-perl_2.24-1.1_amd64 
NAME
Template::Manual::Config - Configuration options
Template Style and Parsing Options
START_TAG, END_TAG
The "START_TAG" and "END_TAG" options are used to specify character sequences or regular
expressions that mark the start and end of a template directive. The default values for
"START_TAG" and "END_TAG" are '"[%"' and '"%]"' respectively, giving us the familiar
directive style:
[% example %]
Any Perl regex characters can be used and therefore should be escaped (or use the Perl
"quotemeta" function) if they are intended to represent literal characters.
my $template = Template->new({
START_TAG => quotemeta('<+'),
END_TAG => quotemeta('+>'),
});
Example:
<+ INCLUDE foobar +>
The "TAGS" directive can also be used to set the "START_TAG" and "END_TAG" values on a
per-template file basis.
[% TAGS <+ +> %]
TAG_STYLE
The "TAG_STYLE" option can be used to set both "START_TAG" and "END_TAG" according to pre-
defined tag styles.
my $template = Template->new({
TAG_STYLE => 'star',
});
Available styles are:
template [% ... %] (default)
template1 [% ... %] or %% ... %% (TT version 1)
metatext %% ... %% (Text::MetaText)
star [* ... *] (TT alternate)
php <? ... ?> (PHP)
asp <% ... %> (ASP)
mason <% ... > (HTML::Mason)
html <!-- ... --> (HTML comments)
Any values specified for "START_TAG" and/or "END_TAG" will override those defined by a
"TAG_STYLE".
The "TAGS" directive may also be used to set a "TAG_STYLE"
[% TAGS html %]
<!-- INCLUDE header -->
PRE_CHOMP, POST_CHOMP
Anything outside a directive tag is considered plain text and is generally passed through
unaltered (but see the INTERPOLATE option). This includes all whitespace and newlines
characters surrounding directive tags. Directives that don't generate any output will
leave gaps in the output document.
Example:
Foo
[% a = 10 %]
Bar
Output:
Foo
Bar
The "PRE_CHOMP" and "POST_CHOMP" options can help to clean up some of this extraneous
whitespace. Both are disabled by default.
my $template = Template-E<gt>new({
PRE_CHOMP => 1,
POST_CHOMP => 1,
});
With "PRE_CHOMP" set to 1, the newline and whitespace preceding a directive at the start
of a line will be deleted. This has the effect of concatenating a line that starts with a
directive onto the end of the previous line.
Foo <----------.
|
,---(PRE_CHOMP)----'
|
`-- [% a = 10 %] --.
|
,---(POST_CHOMP)---'
|
`-> Bar
With "POST_CHOMP" set to 1, any whitespace after a directive up to and including the
newline will be deleted. This has the effect of joining a line that ends with a directive
onto the start of the next line.
If "PRE_CHOMP" or "POST_CHOMP" is set to 2, all whitespace including any number of newline
will be removed and replaced with a single space. This is useful for HTML, where
(usually) a contiguous block of whitespace is rendered the same as a single space.
With "PRE_CHOMP" or "POST_CHOMP" set to 3, all adjacent whitespace (including newlines)
will be removed entirely.
These values are defined as "CHOMP_NONE", "CHOMP_ONE", "CHOMP_COLLAPSE" and "CHOMP_GREEDY"
constants in the Template::Constants module. "CHOMP_ALL" is also defined as an alias for
"CHOMP_ONE" to provide backwards compatability with earlier version of the Template
Toolkit.
Additionally the chomp tag modifiers listed below may also be used for the "PRE_CHOMP" and
"POST_CHOMP" configuration.
my $template = Template->new({
PRE_CHOMP => '~',
POST_CHOMP => '-',
});
"PRE_CHOMP" and "POST_CHOMP" can be activated for individual directives by placing a '"-"'
immediately at the start and/or end of the directive.
[% FOREACH user IN userlist %]
[%- user -%]
[% END %]
This has the same effect as "CHOMP_ONE" in removing all whitespace before or after the
directive up to and including the newline. The template will be processed as if written:
[% FOREACH user IN userlist %][% user %][% END %]
To remove all whitespace including any number of newlines, use the '"~"' character
instead.
[% FOREACH user IN userlist %]
[%~ user ~%]
[% END %]
To collapse all whitespace to a single space, use the '"="' character.
[% FOREACH user IN userlist %]
[%= user =%]
[% END %]
Here the template is processed as if written:
[% FOREACH user IN userlist %] [% user %] [% END %]
If you have "PRE_CHOMP" or "POST_CHOMP" set as configuration options then you can use
'"+"' to disable any chomping options (i.e. leave the whitespace intact) on a per-
directive basis.
[% FOREACH user IN userlist %]
User: [% user +%]
[% END %]
With "POST_CHOMP" set to "CHOMP_ONE", the above example would be parsed as if written:
[% FOREACH user IN userlist %]User: [% user %]
[% END %]
For reference, the "PRE_CHOMP" and "POST_CHOMP" configuration options may be set to any of
the following:
Constant Value Tag Modifier
----------------------------------
CHOMP_NONE 0 +
CHOMP_ONE 1 -
CHOMP_COLLAPSE 2 =
CHOMP_GREEDY 3 ~
TRIM
The "TRIM" option can be set to have any leading and trailing whitespace automatically
removed from the output of all template files and "BLOCK"s.
By example, the following "BLOCK" definition
[% BLOCK foo %]
Line 1 of foo
[% END %]
will be processed is as ""\nLine 1 of foo\n"". When "INCLUDE"d, the surrounding newlines
will also be introduced.
before
[% INCLUDE foo %]
after
Generated output:
before
Line 1 of foo
after
With the "TRIM" option set to any true value, the leading and trailing newlines (which
count as whitespace) will be removed from the output of the "BLOCK".
before
Line 1 of foo
after
The "TRIM" option is disabled (0) by default.
INTERPOLATE
The "INTERPOLATE" flag, when set to any true value will cause variable references in plain
text (i.e. not surrounded by "START_TAG" and "END_TAG") to be recognised and interpolated
accordingly.
my $template = Template->new({
INTERPOLATE => 1,
});
Variables should be prefixed by a '"$"' to identify them. Curly braces can be used in the
familiar Perl/shell style to explicitly scope the variable name where required.
# INTERPOLATE => 0
<a href="http://[% server %]/[% help %]">
<img src="[% images %]/help.gif"></a>
[% myorg.name %]
# INTERPOLATE => 1
<a href="http://$server/$help">
<img src="$images/help.gif"></a>
$myorg.name
# explicit scoping with { }
<img src="$images/${icon.next}.gif">
Note that a limitation in Perl's regex engine restricts the maximum length of an
interpolated template to around 32 kilobytes or possibly less. Files that exceed this
limit in size will typically cause Perl to dump core with a segmentation fault. If you
routinely process templates of this size then you should disable "INTERPOLATE" or split
the templates in several smaller files or blocks which can then be joined backed together
via "PROCESS" or "INCLUDE".
ANYCASE
By default, directive keywords should be expressed in UPPER CASE. The "ANYCASE" option
can be set to allow directive keywords to be specified in any case.
# ANYCASE => 0 (default)
[% INCLUDE foobar %] # OK
[% include foobar %] # ERROR
[% include = 10 %] # OK, 'include' is a variable
# ANYCASE => 1
[% INCLUDE foobar %] # OK
[% include foobar %] # OK
[% include = 10 %] # ERROR, 'include' is reserved word
One side-effect of enabling "ANYCASE" is that you cannot use a variable of the same name
as a reserved word, regardless of case. The reserved words are currently:
GET CALL SET DEFAULT INSERT INCLUDE PROCESS WRAPPER
IF UNLESS ELSE ELSIF FOR FOREACH WHILE SWITCH CASE
USE PLUGIN FILTER MACRO PERL RAWPERL BLOCK META
TRY THROW CATCH FINAL NEXT LAST BREAK RETURN STOP
CLEAR TO STEP AND OR NOT MOD DIV END
The only lower case reserved words that cannot be used for variables, regardless of the
"ANYCASE" option, are the operators:
and or not mod div
Template Files and Blocks
INCLUDE_PATH
The "INCLUDE_PATH" is used to specify one or more directories in which template files are
located. When a template is requested that isn't defined locally as a "BLOCK", each of
the "INCLUDE_PATH" directories is searched in turn to locate the template file. Multiple
directories can be specified as a reference to a list or as a single string where each
directory is delimited by '":"'.
my $template = Template->new({
INCLUDE_PATH => '/usr/local/templates',
});
my $template = Template->new({
INCLUDE_PATH => '/usr/local/templates:/tmp/my/templates',
});
my $template = Template->new({
INCLUDE_PATH => [ '/usr/local/templates',
'/tmp/my/templates' ],
});
On Win32 systems, a little extra magic is invoked, ignoring delimiters that have '":"'
followed by a '"/"' or '"\"'. This avoids confusion when using directory names like
'"C:\Blah Blah"'.
When specified as a list, the "INCLUDE_PATH" path can contain elements which dynamically
generate a list of "INCLUDE_PATH" directories. These generator elements can be specified
as a reference to a subroutine or an object which implements a "paths()" method.
my $template = Template->new({
INCLUDE_PATH => [ '/usr/local/templates',
\&incpath_generator,
My::IncPath::Generator->new( ... ) ],
});
Each time a template is requested and the "INCLUDE_PATH" examined, the subroutine or
object method will be called. A reference to a list of directories should be returned.
Generator subroutines should report errors using "die()". Generator objects should return
undef and make an error available via its "error()" method.
For example:
sub incpath_generator {
# ...some code...
if ($all_is_well) {
return \@list_of_directories;
}
else {
die "cannot generate INCLUDE_PATH...\n";
}
}
or:
package My::IncPath::Generator;
# Template::Base (or Class::Base) provides error() method
use Template::Base;
use base qw( Template::Base );
sub paths {
my $self = shift;
# ...some code...
if ($all_is_well) {
return \@list_of_directories;
}
else {
return $self->error("cannot generate INCLUDE_PATH...\n");
}
}
1;
DELIMITER
Used to provide an alternative delimiter character sequence for separating paths specified
in the "INCLUDE_PATH". The default value for "DELIMITER" is '":"'.
my $template = Template->new({
DELIMITER => '; ',
INCLUDE_PATH => 'C:/HERE/NOW; D:/THERE/THEN',
});
On Win32 systems, the default delimiter is a little more intelligent, splitting paths only
on '":"' characters that aren't followed by a '"/"'. This means that the following should
work as planned, splitting the "INCLUDE_PATH" into 2 separate directories, "C:/foo" and
"C:/bar".
# on Win32 only
my $template = Template->new({
INCLUDE_PATH => 'C:/Foo:C:/Bar'
});
However, if you're using Win32 then it's recommended that you explicitly set the
"DELIMITER" character to something else (e.g. '";"') rather than rely on this subtle
magic.
ABSOLUTE
The "ABSOLUTE" flag is used to indicate if templates specified with absolute filenames
(e.g. '"/foo/bar"') should be processed. It is disabled by default and any attempt to
load a template by such a name will cause a '"file"' exception to be raised.
my $template = Template->new({
ABSOLUTE => 1,
});
# this is why it's disabled by default
[% INSERT /etc/passwd %]
On Win32 systems, the regular expression for matching absolute pathnames is tweaked
slightly to also detect filenames that start with a driver letter and colon, such as:
C:/Foo/Bar
RELATIVE
The "RELATIVE" flag is used to indicate if templates specified with filenames relative to
the current directory (e.g. '"./foo/bar"' or '"../../some/where/else"') should be loaded.
It is also disabled by default, and will raise a '"file"' error if such template names are
encountered.
my $template = Template->new({
RELATIVE => 1,
});
[% INCLUDE ../logs/error.log %]
DEFAULT
The "DEFAULT" option can be used to specify a default template which should be used
whenever a specified template can't be found in the "INCLUDE_PATH".
my $template = Template->new({
DEFAULT => 'notfound.html',
});
If a non-existant template is requested through the Template process() method, or by an
"INCLUDE", "PROCESS" or "WRAPPER" directive, then the "DEFAULT" template will instead be
processed, if defined. Note that the "DEFAULT" template is not used when templates are
specified with absolute or relative filenames, or as a reference to a input file handle or
text string.
BLOCKS
The "BLOCKS" option can be used to pre-define a default set of template blocks. These
should be specified as a reference to a hash array mapping template names to template
text, subroutines or Template::Document objects.
my $template = Template->new({
BLOCKS => {
header => 'The Header. [% title %]',
footer => sub { return $some_output_text },
another => Template::Document->new({ ... }),
},
});
VIEWS
The VIEWS option can be used to define one or more Template::View objects. They can be
specified as a reference to a hash array or list reference.
my $template = Template->new({
VIEWS => {
my_view => { prefix => 'my_templates/' },
},
});
Be aware of the fact that Perl's hash array are unordered, so if you want to specify
multiple views of which one or more are based on other views, then you should use a list
reference to preserve the order of definition.
my $template = Template->new({
VIEWS => [
bottom => { prefix => 'bottom/' },
middle => { prefix => 'middle/', base => 'bottom' },
top => { prefix => 'top/', base => 'middle' },
],
});
AUTO_RESET
The "AUTO_RESET" option is set by default and causes the local "BLOCKS" cache for the
Template::Context object to be reset on each call to the Template process() method. This
ensures that any "BLOCK"s defined within a template will only persist until that template
is finished processing. This prevents "BLOCK"s defined in one processing request from
interfering with other independent requests subsequently processed by the same context
object.
The "BLOCKS" item may be used to specify a default set of block definitions for the
Template::Context object. Subsequent "BLOCK" definitions in templates will over-ride these
but they will be reinstated on each reset if "AUTO_RESET" is enabled (default), or if the
Template::Context reset() method is called.
RECURSION
The template processor will raise a file exception if it detects direct or indirect
recursion into a template. Setting this option to any true value will allow templates to
include each other recursively.
Template Variables
VARIABLES
The "VARIABLES" option (or "PRE_DEFINE" - they're equivalent) can be used to specify a
hash array of template variables that should be used to pre-initialise the stash when it
is created. These items are ignored if the "STASH" item is defined.
my $template = Template->new({
VARIABLES => {
title => 'A Demo Page',
author => 'Joe Random Hacker',
version => 3.14,
},
};
or
my $template = Template->new({
PRE_DEFINE => {
title => 'A Demo Page',
author => 'Joe Random Hacker',
version => 3.14,
},
};
CONSTANTS
The "CONSTANTS" option can be used to specify a hash array of template variables that are
compile-time constants. These variables are resolved once when the template is compiled,
and thus don't require further resolution at runtime. This results in significantly
faster processing of the compiled templates and can be used for variables that don't
change from one request to the next.
my $template = Template->new({
CONSTANTS => {
title => 'A Demo Page',
author => 'Joe Random Hacker',
version => 3.14,
},
};
CONSTANT_NAMESPACE
Constant variables are accessed via the "constants" namespace by default.
[% constants.title %]
The "CONSTANTS_NAMESPACE" option can be set to specify an alternate namespace.
my $template = Template->new({
CONSTANTS => {
title => 'A Demo Page',
# ...etc...
},
CONSTANTS_NAMESPACE => 'const',
};
In this case the constants would then be accessed as:
[% const.title %]
NAMESPACE
The constant folding mechanism described above is an example of a namespace handler.
Namespace handlers can be defined to provide alternate parsing mechanisms for variables in
different namespaces.
Under the hood, the Template module converts a constructor configuration such as:
my $template = Template->new({
CONSTANTS => {
title => 'A Demo Page',
# ...etc...
},
CONSTANTS_NAMESPACE => 'const',
};
into one like:
my $template = Template->new({
NAMESPACE => {
const => Template:::Namespace::Constants->new({
title => 'A Demo Page',
# ...etc...
}),
},
};
You can use this mechanism to define multiple constant namespaces, or to install custom
handlers of your own.
my $template = Template->new({
NAMESPACE => {
site => Template:::Namespace::Constants->new({
title => "Wardley's Widgets",
version => 2.718,
}),
author => Template:::Namespace::Constants->new({
name => 'Andy Wardley',
email => 'abw@andywardley.com',
}),
voodoo => My::Namespace::Handler->new( ... ),
},
};
Now you have two constant namespaces, for example:
[% site.title %]
[% author.name %]
as well as your own custom namespace handler installed for the 'voodoo' namespace.
[% voodoo.magic %]
See Template::Namespace::Constants for an example of what a namespace handler looks like
on the inside.
Template Processing Options
The following options are used to specify any additional templates that should be
processed before, after, around or instead of the template passed as the first argument to
the Template process() method. These options can be perform various useful tasks such as
adding standard headers or footers to all pages, wrapping page output in other templates,
pre-defining variables or performing initialisation or cleanup tasks, automatically
generating page summary information, navigation elements, and so on.
The task of processing the template is delegated internally to the Template::Service
module which, unsurprisingly, also has a process() method. Any templates defined by the
"PRE_PROCESS" option are processed first and any output generated is added to the output
buffer. Then the main template is processed, or if one or more "PROCESS" templates are
defined then they are instead processed in turn. In this case, one of the "PROCESS"
templates is responsible for processing the main template, by a directive such as:
[% PROCESS $template %]
The output of processing the main template or the "PROCESS" template(s) is then wrapped in
any "WRAPPER" templates, if defined. "WRAPPER" templates don't need to worry about
explicitly processing the template because it will have been done for them already.
Instead "WRAPPER" templates access the content they are wrapping via the "content"
variable.
wrapper before
[% content %]
wrapper after
This output generated from processing the main template, and/or any "PROCESS" or "WRAPPER"
templates is added to the output buffer. Finally, any "POST_PROCESS" templates are
processed and their output is also added to the output buffer which is then returned.
If the main template throws an exception during processing then any relevant template(s)
defined via the "ERROR" option will be processed instead. If defined and successfully
processed, the output from the error template will be added to the output buffer in place
of the template that generated the error and processing will continue, applying any
"WRAPPER" and "POST_PROCESS" templates. If no relevant "ERROR" option is defined, or if
the error occurs in one of the "PRE_PROCESS", "WRAPPER" or "POST_PROCESS" templates, then
the process will terminate immediately and the error will be returned.
PRE_PROCESS, POST_PROCESS
These values may be set to contain the name(s) of template files (relative to
"INCLUDE_PATH") which should be processed immediately before and/or after each template.
These do not get added to templates processed into a document via directives such as
"INCLUDE", "PROCESS", "WRAPPER" etc.
my $template = Template->new({
PRE_PROCESS => 'header',
POST_PROCESS => 'footer',
};
Multiple templates may be specified as a reference to a list. Each is processed in the
order defined.
my $template = Template->new({
PRE_PROCESS => [ 'config', 'header' ],
POST_PROCESS => 'footer',
};
Alternately, multiple template may be specified as a single string, delimited by '":"'.
This delimiter string can be changed via the "DELIMITER" option.
my $template = Template->new({
PRE_PROCESS => 'config:header',
POST_PROCESS => 'footer',
};
The "PRE_PROCESS" and "POST_PROCESS" templates are evaluated in the same variable context
as the main document and may define or update variables for subsequent use.
config:
[% # set some site-wide variables
bgcolor = '#ffffff'
version = 2.718
%]
header:
[% DEFAULT title = 'My Funky Web Site' %]
<html>
<head>
<title>[% title %]</title>
</head>
<body bgcolor="[% bgcolor %]">
footer:
<hr>
Version [% version %]
</body>
</html>
The Template::Document object representing the main template being processed is available
within "PRE_PROCESS" and "POST_PROCESS" templates as the "template" variable. Metadata
items defined via the "META" directive may be accessed accordingly.
$template->process('mydoc.html', $vars);
mydoc.html:
[% META title = 'My Document Title' %]
blah blah blah
...
header:
<html>
<head>
<title>[% template.title %]</title>
</head>
<body bgcolor="[% bgcolor %]">
PROCESS
The "PROCESS" option may be set to contain the name(s) of template files (relative to
"INCLUDE_PATH") which should be processed instead of the main template passed to the
Template process() method. This can be used to apply consistent wrappers around all
templates, similar to the use of "PRE_PROCESS" and "POST_PROCESS" templates.
my $template = Template->new({
PROCESS => 'content',
};
# processes 'content' instead of 'foo.html'
$template->process('foo.html');
A reference to the original template is available in the "template" variable. Metadata
items can be inspected and the template can be processed by specifying it as a variable
reference (i.e. prefixed by "$") to an "INCLUDE", "PROCESS" or "WRAPPER" directive.
content:
<html>
<head>
<title>[% template.title %]</title>
</head>
<body>
<!-- begin content -->
[% PROCESS $template %]
<!-- end content -->
<hr>
© Copyright [% template.copyright %]
</body>
</html>
foo.html:
[% META
title = 'The Foo Page'
author = 'Fred Foo'
copyright = '2000 Fred Foo'
%]
<h1>[% template.title %]</h1>
Welcome to the Foo Page, blah blah blah
output:
<html>
<head>
<title>The Foo Page</title>
</head>
<body>
<!-- begin content -->
<h1>The Foo Page</h1>
Welcome to the Foo Page, blah blah blah
<!-- end content -->
<hr>
© Copyright 2000 Fred Foo
</body>
</html>
WRAPPER
The "WRAPPER" option can be used to specify one or more templates which should be used to
wrap around the output of the main page template. The main template is processed first
(or any "PROCESS" template(s)) and the output generated is then passed as the "content"
variable to the "WRAPPER" template(s) as they are processed.
my $template = Template->new({
WRAPPER => 'wrapper',
};
# process 'foo' then wrap in 'wrapper'
$template->process('foo', { message => 'Hello World!' });
wrapper:
<wrapper>
[% content %]
</wrapper>
foo:
This is the foo file!
Message: [% message %]
The output generated from this example is:
<wrapper>
This is the foo file!
Message: Hello World!
</wrapper>
You can specify more than one "WRAPPER" template by setting the value to be a reference to
a list of templates. The "WRAPPER" templates will be processed in reverse order with the
output of each being passed to the next (or previous, depending on how you look at it) as
the 'content' variable. It sounds complicated, but the end result is that it just "Does
The Right Thing" to make wrapper templates nest in the order you specify.
my $template = Template->new({
WRAPPER => [ 'outer', 'inner' ],
};
# process 'foo' then wrap in 'inner', then in 'outer'
$template->process('foo', { message => 'Hello World!' });
outer:
<outer>
[% content %]
</outer>
inner:
<inner>
[% content %]
</inner>
The output generated is then:
<outer>
<inner>
This is the foo file!
Message: Hello World!
</inner>
</outer>
One side-effect of the "inside-out" processing of the "WRAPPER" configuration item (and
also the "WRAPPER" directive) is that any variables set in the template being wrapped will
be visible to the template doing the wrapping, but not the other way around.
You can use this to good effect in allowing page templates to set pre-defined values which
are then used in the wrapper templates. For example, our main page template 'foo' might
look like this:
foo:
[% page = {
title = 'Foo Page'
subtitle = 'Everything There is to Know About Foo'
author = 'Frank Oliver Octagon'
}
%]
<p>
Welcome to the page that tells you everything about foo
blah blah blah...
</p>
The "foo" template is processed before the wrapper template meaning that the "page" data
structure will be defined for use in the wrapper template.
wrapper:
<html>
<head>
<title>[% page.title %]</title>
</head>
<body>
<h1>[% page.title %]</h1>
<h2>[% page.subtitle %]</h1>
<h3>by [% page.author %]</h3>
[% content %]
</body>
</html>
It achieves the same effect as defining "META" items which are then accessed via the
"template" variable (which you are still free to use within "WRAPPER" templates), but
gives you more flexibility in the type and complexity of data that you can define.
ERROR
The "ERROR" (or "ERRORS" if you prefer) configuration item can be used to name a single
template or specify a hash array mapping exception types to templates which should be used
for error handling. If an uncaught exception is raised from within a template then the
appropriate error template will instead be processed.
If specified as a single value then that template will be processed for all uncaught
exceptions.
my $template = Template->new({
ERROR => 'error.html'
});
If the "ERROR" item is a hash reference the keys are assumed to be exception types and the
relevant template for a given exception will be selected. A "default" template may be
provided for the general case. Note that "ERROR" can be pluralised to "ERRORS" if you
find it more appropriate in this case.
my $template = Template->new({
ERRORS => {
user => 'user/index.html',
dbi => 'error/database',
default => 'error/default',
},
});
In this example, any "user" exceptions thrown will cause the user/index.html template to
be processed, "dbi" errors are handled by error/database and all others by the
error/default template. Any "PRE_PROCESS" and/or "POST_PROCESS" templates will also be
applied to these error templates.
Note that exception types are hierarchical and a "foo" handler will catch all "foo.*"
errors (e.g. "foo.bar", "foo.bar.baz") if a more specific handler isn't defined. Be sure
to quote any exception types that contain periods to prevent Perl concatenating them into
a single string (i.e. "user.passwd" is parsed as 'user'.'passwd').
my $template = Template->new({
ERROR => {
'user.login' => 'user/login.html',
'user.passwd' => 'user/badpasswd.html',
'user' => 'user/index.html',
'default' => 'error/default',
},
});
In this example, any template processed by the $template object, or other templates or
code called from within, can raise a "user.login" exception and have the service redirect
to the user/login.html template. Similarly, a "user.passwd" exception has a specific
handling template, user/badpasswd.html, while all other "user" or "user.*" exceptions
cause a redirection to the user/index.html page. All other exception types are handled by
error/default.
Exceptions can be raised in a template using the "THROW" directive,
[% THROW user.login 'no user id: please login' %]
or by calling the throw() method on the current Template::Context object,
$context->throw('user.passwd', 'Incorrect Password');
$context->throw('Incorrect Password'); # type 'undef'
or from Perl code by calling "die()" with a Template::Exception object,
die (Template::Exception->new('user.denied', 'Invalid User ID'));
or by simply calling die() with an error string. This is automagically caught and
converted to an exception of '"undef"' type which can then be handled in the usual way.
die "I'm sorry Dave, I can't do that";
Note that the '"undef"' we're talking about here is a literal string rather than Perl's
"undef" used to represent undefined values.
Template Runtime Options
EVAL_PERL
This flag is used to indicate if "PERL" and/or "RAWPERL" blocks should be evaluated. It
is disabled by default and any "PERL" or "RAWPERL" blocks encountered will raise
exceptions of type '"perl"' with the message '"EVAL_PERL not set"'. Note however that any
"RAWPERL" blocks should always contain valid Perl code, regardless of the "EVAL_PERL"
flag. The parser will fail to compile templates that contain invalid Perl code in
"RAWPERL" blocks and will throw a '"file"' exception.
When using compiled templates (see "Caching and Compiling Options"), the "EVAL_PERL" has
an affect when the template is compiled, and again when the templates is subsequently
processed, possibly in a different context to the one that compiled it.
If the "EVAL_PERL" is set when a template is compiled, then all "PERL" and "RAWPERL"
blocks will be included in the compiled template. If the "EVAL_PERL" option isn't set,
then Perl code will be generated which always throws a '"perl"' exception with the message
'"EVAL_PERL not set"' whenever the compiled template code is run.
Thus, you must have "EVAL_PERL" set if you want your compiled templates to include "PERL"
and "RAWPERL" blocks.
At some point in the future, using a different invocation of the Template Toolkit, you may
come to process such a pre-compiled template. Assuming the "EVAL_PERL" option was set at
the time the template was compiled, then the output of any "RAWPERL" blocks will be
included in the compiled template and will get executed when the template is processed.
This will happen regardless of the runtime "EVAL_PERL" status.
Regular "PERL" blocks are a little more cautious, however. If the "EVAL_PERL" flag isn't
set for the current context, that is, the one which is trying to process it, then it will
throw the familiar '"perl"' exception with the message, '"EVAL_PERL not set"'.
Thus you can compile templates to include "PERL" blocks, but optionally disable them when
you process them later. Note however that it is possible for a "PERL" block to contain a
Perl ""BEGIN { # some code }"" block which will always get run regardless of the runtime
"EVAL_PERL" status. Thus, if you set "EVAL_PERL" when compiling templates, it is assumed
that you trust the templates to Do The Right Thing. Otherwise you must accept the fact
that there's no bulletproof way to prevent any included code from trampling around in the
living room of the runtime environment, making a real nuisance of itself if it really
wants to. If you don't like the idea of such uninvited guests causing a bother, then you
can accept the default and keep "EVAL_PERL" disabled.
OUTPUT
Default output location or handler. This may be specified as one of: a file name
(relative to "OUTPUT_PATH", if defined, or the current working directory if not specified
absolutely); a file handle (e.g. "GLOB" or IO::Handle) opened for writing; a reference to
a text string to which the output is appended (the string isn't cleared); a reference to a
subroutine which is called, passing the output text as an argument; as a reference to an
array, onto which the content will be "push()"ed; or as a reference to any object that
supports the "print()" method. This latter option includes the "Apache::Request" object
which is passed as the argument to Apache/mod_perl handlers.
example 1 (file name):
my $template = Template->new({
OUTPUT => "/tmp/foo",
});
example 2 (text string):
my $output = '';
my $template = Template->new({
OUTPUT => \$output,
});
example 3 (file handle):
open (TOUT, "> $file") || die "$file: $!\n";
my $template = Template->new({
OUTPUT => \*TOUT,
});
example 4 (subroutine):
sub output { my $out = shift; print "OUTPUT: $out" }
my $template = Template->new({
OUTPUT => \&output,
});
example 5 (array reference):
my $template = Template->new({
OUTPUT => \@output,
})
example 6 (Apache/mod_perl handler):
sub handler {
my $r = shift;
my $t = Template->new({
OUTPUT => $r,
});
...
}
The default "OUTPUT" location be overridden by passing a third parameter to the Template
process() method. This can be specified as any of the above argument types.
$t->process($file, $vars, "/tmp/foo");
$t->process($file, $vars, \$output);
$t->process($file, $vars, \*MYGLOB);
$t->process($file, $vars, \@output);
$t->process($file, $vars, $r); # Apache::Request
...
OUTPUT_PATH
The "OUTPUT_PATH" allows a directory to be specified into which output files should be
written. An output file can be specified by the "OUTPUT" option, or passed by name as the
third parameter to the Template process() method.
my $template = Template->new({
INCLUDE_PATH => "/tmp/src",
OUTPUT_PATH => "/tmp/dest",
});
my $vars = {
...
};
foreach my $file ('foo.html', 'bar.html') {
$template->process($file, $vars, $file)
|| die $template->error();
}
This example will read the input files /tmp/src/foo.html and /tmp/src/bar.html and write
the processed output to /tmp/dest/foo.html and /tmp/dest/bar.html, respectively.
STRICT
By default the Template Toolkit will silently ignore the use of undefined variables (a bad
design decision that I regret).
When the "STRICT" option is set, the use of any undefined variables or values will cause
an exception to be throw. The exception will have a "type" of "var.undefined" and a
message of the form "undefined variable: xxx".
my $template = Template->new(
STRICT => 1
);
DEBUG
The "DEBUG" option can be used to enable debugging within the various different modules
that comprise the Template Toolkit. The Template::Constants module defines a set of
"DEBUG_XXXX" constants which can be combined using the logical OR operator, '"|"'.
use Template::Constants qw( :debug );
my $template = Template->new({
DEBUG => DEBUG_PARSER | DEBUG_PROVIDER,
});
For convenience, you can also provide a string containing a list of lower case debug
options, separated by any non-word characters.
my $template = Template->new({
DEBUG => 'parser, provider',
});
The following "DEBUG_XXXX" flags can be used:
DEBUG_SERVICE
Enables general debugging messages for the Template::Service module.
DEBUG_CONTEXT
Enables general debugging messages for the Template::Context module.
DEBUG_PROVIDER
Enables general debugging messages for the Template::Provider module.
DEBUG_PLUGINS
Enables general debugging messages for the Template::Plugins module.
DEBUG_FILTERS
Enables general debugging messages for the Template::Filters module.
DEBUG_PARSER
This flag causes the Template::Parser to generate debugging messages that show the
Perl code generated by parsing and compiling each template.
DEBUG_UNDEF
This option causes the Template Toolkit to throw an '"undef"' error whenever it
encounters an undefined variable value.
DEBUG_DIRS
This option causes the Template Toolkit to generate comments indicating the source
file, line and original text of each directive in the template. These comments are
embedded in the template output using the format defined in the "DEBUG_FORMAT"
configuration item, or a simple default format if unspecified.
For example, the following template fragment:
Hello World
would generate this output:
## input text line 1 : ##
Hello
## input text line 2 : World ##
World
DEBUG_ALL
Enables all debugging messages.
DEBUG_CALLER
This option causes all debug messages that aren't newline terminated to have the file
name and line number of the caller appended to them.
DEBUG_FORMAT
The "DEBUG_FORMAT" option can be used to specify a format string for the debugging
messages generated via the "DEBUG_DIRS" option described above. Any occurances of $file,
$line or $text will be replaced with the current file name, line or directive text,
respectively. Notice how the format is single quoted to prevent Perl from interpolating
those tokens as variables.
my $template = Template->new({
DEBUG => 'dirs',
DEBUG_FORMAT => '<!-- $file line $line : [% $text %] -->',
});
The following template fragment:
[% foo = 'World' %]
Hello [% foo %]
would then generate this output:
<!-- input text line 2 : [% foo = 'World' %] -->
Hello <!-- input text line 3 : [% foo %] -->World
The DEBUG directive can also be used to set a debug format within a template.
[% DEBUG format '<!-- $file line $line : [% $text %] -->' %]
Caching and Compiling Options
CACHE_SIZE
The Template::Provider module caches compiled templates to avoid the need to re-parse
template files or blocks each time they are used. The "CACHE_SIZE" option is used to limit
the number of compiled templates that the module should cache.
By default, the "CACHE_SIZE" is undefined and all compiled templates are cached. When set
to any positive value, the cache will be limited to storing no more than that number of
compiled templates. When a new template is loaded and compiled and the cache is full
(i.e. the number of entries == "CACHE_SIZE"), the least recently used compiled template is
discarded to make room for the new one.
The "CACHE_SIZE" can be set to 0 to disable caching altogether.
my $template = Template->new({
CACHE_SIZE => 64, # only cache 64 compiled templates
});
my $template = Template->new({
CACHE_SIZE => 0, # don't cache any compiled templates
});
As well as caching templates as they are found, the Template::Provider also implements
negative caching to keep track of templates that are not found. This allows the provider
to quickly decline a request for a template that it has previously failed to locate,
saving the effort of going to look for it again. This is useful when an "INCLUDE_PATH"
includes multiple providers, ensuring that the request is passed down through the
providers as quickly as possible.
STAT_TTL
This value can be set to control how long the Template::Provider will keep a template
cached in memory before checking to see if the source template has changed.
my $provider = Template::Provider->new({
STAT_TTL => 60, # one minute
});
The default value is 1 (second). You'll probably want to set this to a higher value if
you're running the Template Toolkit inside a persistent web server application (e.g.
mod_perl). For example, set it to 60 and the provider will only look for changes to
templates once a minute at most. However, during development (or any time you're making
frequent changes to templates) you'll probably want to keep it set to a low value so that
you don't have to wait for the provider to notice that your templates have changed.
COMPILE_EXT
From version 2 onwards, the Template Toolkit has the ability to compile templates to Perl
code and save them to disk for subsequent use (i.e. cache persistence). The "COMPILE_EXT"
option may be provided to specify a filename extension for compiled template files. It is
undefined by default and no attempt will be made to read or write any compiled template
files.
my $template = Template->new({
COMPILE_EXT => '.ttc',
});
If "COMPILE_EXT" is defined (and "COMPILE_DIR" isn't, see below) then compiled template
files with the "COMPILE_EXT" extension will be written to the same directory from which
the source template files were loaded.
Compiling and subsequent reuse of templates happens automatically whenever the
"COMPILE_EXT" or "COMPILE_DIR" options are set. The Template Toolkit will automatically
reload and reuse compiled files when it finds them on disk. If the corresponding source
file has been modified since the compiled version as written, then it will load and re-
compile the source and write a new compiled version to disk.
This form of cache persistence offers significant benefits in terms of time and resources
required to reload templates. Compiled templates can be reloaded by a simple call to
Perl's "require()", leaving Perl to handle all the parsing and compilation. This is a
Good Thing.
COMPILE_DIR
The "COMPILE_DIR" option is used to specify an alternate directory root under which
compiled template files should be saved.
my $template = Template->new({
COMPILE_DIR => '/tmp/ttc',
});
The "COMPILE_EXT" option may also be specified to have a consistent file extension added
to these files.
my $template1 = Template->new({
COMPILE_DIR => '/tmp/ttc',
COMPILE_EXT => '.ttc1',
});
my $template2 = Template->new({
COMPILE_DIR => '/tmp/ttc',
COMPILE_EXT => '.ttc2',
});
When "COMPILE_EXT" is undefined, the compiled template files have the same name as the
original template files, but reside in a different directory tree.
Each directory in the "INCLUDE_PATH" is replicated in full beneath the "COMPILE_DIR"
directory. This example:
my $template = Template->new({
COMPILE_DIR => '/tmp/ttc',
INCLUDE_PATH => '/home/abw/templates:/usr/share/templates',
});
would create the following directory structure:
/tmp/ttc/home/abw/templates/
/tmp/ttc/usr/share/templates/
Files loaded from different "INCLUDE_PATH" directories will have their compiled forms save
in the relevant "COMPILE_DIR" directory.
On Win32 platforms a filename may by prefixed by a drive letter and colon. e.g.
C:/My Templates/header
The colon will be silently stripped from the filename when it is added to the
"COMPILE_DIR" value(s) to prevent illegal filename being generated. Any colon in
"COMPILE_DIR" elements will be left intact. For example:
# Win32 only
my $template = Template->new({
DELIMITER => ';',
COMPILE_DIR => 'C:/TT2/Cache',
INCLUDE_PATH => 'C:/TT2/Templates;D:/My Templates',
});
This would create the following cache directories:
C:/TT2/Cache/C/TT2/Templates
C:/TT2/Cache/D/My Templates
Plugins and Filters
PLUGINS
The "PLUGINS" options can be used to provide a reference to a hash array that maps plugin
names to Perl module names. A number of standard plugins are defined (e.g. "table",
"format", "cgi", etc.) which map to their corresponding "Template::Plugin::*"
counterparts. These can be redefined by values in the "PLUGINS" hash.
my $template = Template->new({
PLUGINS => {
cgi => 'MyOrg::Template::Plugin::CGI',
foo => 'MyOrg::Template::Plugin::Foo',
bar => 'MyOrg::Template::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.
The "USE" directive is used to create plugin objects and does so by calling the plugin()
method on the current Template::Context object. If the plugin name is defined in the
"PLUGINS" hash then the corresponding Perl module is loaded via "require()". The context
then calls the load() class method which should return the class name (default and general
case) or a prototype object against which the new() method can be called to instantiate
individual plugin objects.
If the plugin name is not defined in the "PLUGINS" hash then the "PLUGIN_BASE" and/or
"LOAD_PERL" options come into effect.
PLUGIN_BASE
If a plugin is not defined in the "PLUGINS" hash then the "PLUGIN_BASE" is used to attempt
to construct a correct Perl module name which can be successfully loaded.
The "PLUGIN_BASE" can be specified as a reference to an array of module namespaces, or as
a single value which is automatically converted to a list. The default "PLUGIN_BASE"
value ("Template::Plugin") is then added to the end of this list.
example 1:
my $template = Template->new({
PLUGIN_BASE => 'MyOrg::Template::Plugin',
});
[% USE Foo %] # => MyOrg::Template::Plugin::Foo
or Template::Plugin::Foo
example 2:
my $template = Template->new({
PLUGIN_BASE => [ 'MyOrg::Template::Plugin',
'YourOrg::Template::Plugin' ],
});
template:
[% USE Foo %] # => MyOrg::Template::Plugin::Foo
or YourOrg::Template::Plugin::Foo
or Template::Plugin::Foo
If you don't want the default "Template::Plugin" namespace added to the end of the
"PLUGIN_BASE", then set the $Template::Plugins::PLUGIN_BASE variable to a false value
before calling the new() Template#new() constructor method. This is shown in the example
below where the "Foo" plugin is located as "My::Plugin::Foo" or "Your::Plugin::Foo" but
not as "Template::Plugin::Foo".
example 3:
use Template::Plugins;
$Template::Plugins::PLUGIN_BASE = '';
my $template = Template->new({
PLUGIN_BASE => [ 'My::Plugin',
'Your::Plugin' ],
});
template:
[% USE Foo %] # => My::Plugin::Foo
or Your::Plugin::Foo
LOAD_PERL
If a plugin cannot be loaded using the "PLUGINS" or "PLUGIN_BASE" approaches then the
provider can make a final attempt to load the module without prepending any prefix to the
module path. This allows regular Perl modules (i.e. those that don't reside in the
Template::Plugin or some other such namespace) to be loaded and used as plugins.
By default, the "LOAD_PERL" option is set to 0 and no attempt will be made to load any
Perl modules that aren't named explicitly in the "PLUGINS" hash or reside in a package as
named by one of the "PLUGIN_BASE" components.
Plugins loaded using the "PLUGINS" or "PLUGIN_BASE" receive a reference to the current
context object as the first argument to the new() constructor. Modules loaded using
"LOAD_PERL" are assumed to not conform to the plugin interface. They must provide a
"new()" class method for instantiating objects but it will not receive a reference to the
context as the first argument.
Plugin modules should provide a load() class method (or inherit the default one from the
Template::Plugin base class) which is called the first time the plugin is loaded. Regular
Perl modules need not. In all other respects, regular Perl objects and Template Toolkit
plugins are identical.
If a particular Perl module does not conform to the common, but not unilateral, "new()"
constructor convention then a simple plugin wrapper can be written to interface to it.
FILTERS
The "FILTERS" option can be used to specify custom filters which can then be used with the
"FILTER" directive like any other. These are added to the standard filters which are
available by default. Filters specified via this option will mask any standard filters of
the same name.
The "FILTERS" option should be specified as a reference to a hash array in which each key
represents the name of a filter. The corresponding value should contain a reference to an
array containing a subroutine reference and a flag which indicates if the filter is static
(0) or dynamic (1). A filter may also be specified as a solitary subroutine reference and
is assumed to be static.
$template = Template->new({
FILTERS => {
'sfilt1' => \&static_filter, # static
'sfilt2' => [ \&static_filter, 0 ], # same as above
'dfilt1' => [ \&dyanamic_filter_factory, 1 ],
},
});
Additional filters can be specified at any time by calling the define_filter() method on
the current Template::Context object. The method accepts a filter name, a reference to a
filter subroutine and an optional flag to indicate if the filter is dynamic.
my $context = $template->context();
$context->define_filter('new_html', \&new_html);
$context->define_filter('new_repeat', \&new_repeat, 1);
Static filters are those where a single subroutine reference is used for all invocations
of a particular filter. Filters that don't accept any configuration parameters (e.g.
"html") can be implemented statically. The subroutine reference is simply returned when
that particular filter is requested. The subroutine is called to filter the output of a
template block which is passed as the only argument. The subroutine should return the
modified text.
sub static_filter {
my $text = shift;
# do something to modify $text...
return $text;
}
The following template fragment:
[% FILTER sfilt1 %]
Blah blah blah.
[% END %]
is approximately equivalent to:
&static_filter("\nBlah blah blah.\n");
Filters that can accept parameters (e.g. "truncate") should be implemented dynamically.
In this case, the subroutine is taken to be a filter 'factory' that is called to create a
unique filter subroutine each time one is requested. A reference to the current
Template::Context object is passed as the first parameter, followed by any additional
parameters specified. The subroutine should return another subroutine reference (usually
a closure) which implements the filter.
sub dynamic_filter_factory {
my ($context, @args) = @_;
return sub {
my $text = shift;
# do something to modify $text...
return $text;
}
}
The following template fragment:
[% FILTER dfilt1(123, 456) %]
Blah blah blah
[% END %]
is approximately equivalent to:
my $filter = &dynamic_filter_factory($context, 123, 456);
&$filter("\nBlah blah blah.\n");
See the "FILTER" directive for further examples.
Customisation and Extension
LOAD_TEMPLATES
The "LOAD_TEMPLATES" option can be used to provide a reference to a list of
Template::Provider objects or sub-classes thereof which will take responsibility for
loading and compiling templates.
my $template = Template->new({
LOAD_TEMPLATES => [
MyOrg::Template::Provider->new({ ... }),
Template::Provider->new({ ... }),
],
});
When a "PROCESS", "INCLUDE" or "WRAPPER" directive is encountered, the named template may
refer to a locally defined "BLOCK" or a file relative to the "INCLUDE_PATH" (or an
absolute or relative path if the appropriate "ABSOLUTE" or "RELATIVE" options are set). If
a "BLOCK" definition can't be found (see the Template::Context template() method for a
discussion of "BLOCK" locality) then each of the "LOAD_TEMPLATES" provider objects is
queried in turn via the fetch() method to see if it can supply the required template.
Each provider can return a compiled template, an error, or decline to service the request
in which case the responsibility is passed to the next provider. If none of the providers
can service the request then a 'not found' error is returned. The same basic provider
mechanism is also used for the "INSERT" directive but it bypasses any "BLOCK" definitions
and doesn't attempt is to parse or process the contents of the template file.
If "LOAD_TEMPLATES" is undefined, a single default provider will be instantiated using the
current configuration parameters. For example, the Template::Provider "INCLUDE_PATH"
option can be specified in the Template configuration and will be correctly passed to the
provider's constructor method.
my $template = Template->new({
INCLUDE_PATH => '/here:/there',
});
LOAD_PLUGINS
The "LOAD_PLUGINS" options can be used to specify a list of provider objects (i.e. they
implement the fetch() method) which are responsible for loading and instantiating template
plugin objects. The Template::Context plugin() method queries each provider in turn in a
"Chain of Responsibility" as per the template() and filter() methods.
my $template = Template->new({
LOAD_PLUGINS => [
MyOrg::Template::Plugins->new({ ... }),
Template::Plugins->new({ ... }),
],
});
By default, a single Template::Plugins object is created using the current configuration
hash. Configuration items destined for the Template::Plugins constructor may be added to
the Template constructor.
my $template = Template->new({
PLUGIN_BASE => 'MyOrg::Template::Plugins',
LOAD_PERL => 1,
});
LOAD_FILTERS
The "LOAD_FILTERS" option can be used to specify a list of provider objects (i.e. they
implement the fetch() method) which are responsible for returning and/or creating filter
subroutines. The Template::Context filter() method queries each provider in turn in a
"Chain of Responsibility" as per the template() and plugin() methods.
my $template = Template->new({
LOAD_FILTERS => [
MyTemplate::Filters->new(),
Template::Filters->new(),
],
});
By default, a single Template::Filters object is created for the "LOAD_FILTERS" list.
TOLERANT
The "TOLERANT" flag is used by the various Template Toolkit provider modules
(Template::Provider, Template::Plugins, Template::Filters) to control their behaviour when
errors are encountered. By default, any errors are reported as such, with the request for
the particular resource ("template", "plugin", "filter") being denied and an exception
raised.
When the "TOLERANT" flag is set to any true values, errors will be silently ignored and
the provider will instead return "STATUS_DECLINED". This allows a subsequent provider to
take responsibility for providing the resource, rather than failing the request outright.
If all providers decline to service the request, either through tolerated failure or a
genuine disinclination to comply, then a '"<resource> not found"' exception is raised.
SERVICE
A reference to a Template::Service object, or sub-class thereof, to which the Template
module should delegate. If unspecified, a Template::Service object is automatically
created using the current configuration hash.
my $template = Template->new({
SERVICE => MyOrg::Template::Service->new({ ... }),
});
CONTEXT
A reference to a Template::Context object which is used to define a specific environment
in which template are processed. A Template::Context object is passed as the only
parameter to the Perl subroutines that represent "compiled" template documents. Template
subroutines make callbacks into the context object to access Template Toolkit
functionality, for example, to to "INCLUDE" or "PROCESS" another template (include() and
process() methods, respectively), to "USE" a plugin (plugin()) or instantiate a filter
(filter()) or to access the stash (stash()) which manages variable definitions via the
get() and set() methods.
my $template = Template->new({
CONTEXT => MyOrg::Template::Context->new({ ... }),
});
STASH
A reference to a Template::Stash object or sub-class which will take responsibility for
managing template variables.
my $stash = MyOrg::Template::Stash->new({ ... });
my $template = Template->new({
STASH => $stash,
});
If unspecified, a default stash object is created using the "VARIABLES" configuration item
to initialise the stash variables.
my $template = Template->new({
VARIABLES => {
id => 'abw',
name => 'Andy Wardley',
},
};
PARSER
The Template::Parser module implements a parser object for compiling templates into Perl
code which can then be executed. A default object of this class is created automatically
and then used by the Template::Provider whenever a template is loaded and requires
compilation. The "PARSER" option can be used to provide a reference to an alternate
parser object.
my $template = Template->new({
PARSER => MyOrg::Template::Parser->new({ ... }),
});
GRAMMAR
The "GRAMMAR" configuration item can be used to specify an alternate grammar for the
parser. This allows a modified or entirely new template language to be constructed and
used by the Template Toolkit.
Source templates are compiled to Perl code by the Template::Parser using the
Template::Grammar (by default) to define the language structure and semantics. Compiled
templates are thus inherently "compatible" with each other and there is nothing to prevent
any number of different template languages being compiled and used within the same
Template Toolkit processing environment (other than the usual time and memory
constraints).
The Template::Grammar file is constructed from a YACC like grammar (using "Parse::YAPP")
and a skeleton module template. These files are provided, along with a small script to
rebuild the grammar, in the parser sub-directory of the distribution.
You don't have to know or worry about these unless you want to hack on the template
language or define your own variant. There is a README file in the same directory which
provides some small guidance but it is assumed that you know what you're doing if you
venture herein. If you grok LALR parsers, then you should find it comfortably familiar.
By default, an instance of the default Template::Grammar will be created and used
automatically if a "GRAMMAR" item isn't specified.
use MyOrg::Template::Grammar;
my $template = Template->new({
GRAMMAR = MyOrg::Template::Grammar->new();
});