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.
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();
});