|
Template::Manual::Config - Configuration options |
Template::Manual::Config - Configuration options
This section contains details of all the configuration options that can be used to customise the behaviour and extend the features of the Template Toolkit.
[% 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 <+ +> %]
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 over-ride those defined by a TAG_STYLE.
The TAGS directive may also be used to set a TAG_STYLE
[% TAGS html %]
<!-- INCLUDE header -->
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->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, then instead of removing all the whitespace, the whitespace will be collapsed to a single space. This is useful for HTML, where (usually) a contiguous block of whitespace is rendered the same as a single space.
You may use the CHOMP_NONE, CHOMP_ALL, and CHOMP_COLLAPSE constants from the Template::Constants module to deactivate chomping, remove all whitespace, or collapse whitespace to a single space.
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 = userlist %]
[%- user -%]
[% END %]
The '-' characters activate both PRE_CHOMP and POST_CHOMP for the one directive '[%- name -%]'. Thus, the template will be processed as if written:
[% FOREACH user = userlist %][% user %][% END %]
Note that this is the same as if PRE_CHOMP and POST_CHOMP were set to CHOMP_ALL; the only way to get the CHOMP_COLLAPSE behavior is to set PRE_CHOMP or POST_CHOMP accordingly. If PRE_CHOMP or POST_CHOMP is already set to CHOMP_COLLAPSE, using '-' will give you CHOMP_COLLAPSE behavior, not CHOMP_ALL behavior.
Similarly, '+' characters can be used to disable PRE_CHOMP or POST_CHOMP (i.e. leave the whitespace/newline intact) options on a per-directive basis.
[% FOREACH user = userlist %]
User: [% user +%]
[% END %]
With POST_CHOMP enabled, the above example would be parsed as if written:
[% FOREACH user = userlist %]User: [% user %]
[% END %]
By example, the following BLOCK definition
[% BLOCK foo %]
Line 1 of foo
[% END %]
will be processed is as ``\nLine 1 of foo\n''. When INCLUDEd, the surrounding newlines will also be introduced.
before
[% INCLUDE foo %]
after
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.
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 => 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
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;
# tolerate Silly Billy's file system conventions
my $template = Template->new({
DELIMITER => '; ',
INCLUDE_PATH => 'C:/HERE/NOW; D:/THERE/THEN',
});
# better solution: install Linux! :-)
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.
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
my $template = Template->new({
RELATIVE => 1,
});
[% INCLUDE ../logs/error.log %]
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.
my $template = Template->new({
BLOCKS => {
header => 'The Header. [% title %]',
footer => sub { return $some_output_text },
another => Template::Document->new({ ... }),
},
});
process() method. This ensures that any BLOCKs defined
within a template will only persist until that template is finished
processing. This prevents BLOCKs 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.
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,
},
};
my $template = Template->new({
CONSTANTS => {
title => 'A Demo Page',
author => 'Joe Random Hacker',
version => 3.14,
},
};
[% 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 %]
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 2 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.
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.
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 %]">
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>
[% PROCESS $template %]
<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>
<h1>The Foo Page</h1>
Welcome to the Foo Page, blah blah blah
<hr>
© Copyright 2000 Fred Foo
</body>
</html>
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.
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";
When using compiled templates (see COMPILE_EXT and COMPILE_DIR), 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.
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, "bar");
$t->process($file, $vars, \*MYGLOB);
$t->process($file, $vars, \@output);
$t->process($file, $vars, $r); # Apache::Request
...
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.
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:
For example, the following template fragment:
Hello World
would generate this output:
## input text line 1 : ##
Hello
## input text line 2 : World ##
World
$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 %] -->' %]
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
});
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.
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
my $template = Template->new({
PLUGINS => {
cgi => 'MyOrg::Template::Plugin::CGI',
foo => 'MyOrg::Template::Plugin::Foo',
bar => 'MyOrg::Template::Plugin::Bar',
},
});
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.
The PLUGIN_BASE can be specified as a single value or as a reference to an array of multiple values. The default PLUGIN_BASE value, 'Template::Plugin', is always added the the end of the PLUGIN_BASE list (a single value is first converted to a list). Each value should contain a Perl package name to which the requested plugin name is appended.
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' ],
});
[% USE Foo %] # => MyOrg::Template::Plugin::Foo
or YourOrg::Template::Plugin::Foo
or Template::Plugin::Foo
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.
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.
# VERSION 1
[% $foo %] === [% foo %]
[% $hash.$key %] === [% hash.key %]
To interpolate a variable value the '${' ... '}' construct was used. Typically, one would do this to index into a hash array when the key value was stored in a variable.
example:
my $vars = {
users => {
aba => { name => 'Alan Aardvark', ... },
abw => { name => 'Andy Wardley', ... },
...
},
uid => 'aba',
...
};
$template->process('user/home.html', $vars)
|| die $template->error(), "\n";
'user/home.html':
[% user = users.${uid} %] # users.aba
Name: [% user.name %] # Alan Aardvark
This was inconsistent with double quoted strings and also the INTERPOLATE mode, where a leading '$' in text was enough to indicate a variable for interpolation, and the additional curly braces were used to delimit variable names where necessary. Note that this use is consistent with UNIX and Perl conventions, among others.
# double quoted string interpolation
[% name = "$title ${user.name}" %]
# INTERPOLATE = 1
<img src="$images/help.gif"></a>
<img src="$images/${icon.next}.gif">
For version 2, these inconsistencies have been removed and the syntax clarified. A leading '$' on a variable is now used exclusively to indicate that the variable name should be interpolated (e.g. subsituted for its value) before being used. The earlier example from version 1:
# VERSION 1
[% user = users.${uid} %]
Name: [% user.name %]
can now be simplified in version 2 as:
# VERSION 2
[% user = users.$uid %]
Name: [% user.name %]
The leading dollar is no longer ignored and has the same effect of interpolation as '${' ... '}' in version 1. The curly braces may still be used to explicitly scope the interpolated variable name where necessary.
e.g.
[% user = users.${me.id} %]
Name: [% user.name %]
The rule applies for all variables, both within directives and in plain text if processed with the INTERPOLATE option. This means that you should no longer (if you ever did) add a leading '$' to a variable inside a directive, unless you explicitly want it to be interpolated.
One obvious side-effect is that any version 1 templates with variables using a leading '$' will no longer be processed as expected. Given the following variable definitions,
[% foo = 'bar'
bar = 'baz'
%]
version 1 would interpret the following as:
# VERSION 1
[% $foo %] => [% GET foo %] => bar
whereas version 2 interprets it as:
# VERSION 2
[% $foo %] => [% GET $foo %] => [% GET bar %] => baz
In version 1, the '$' is ignored and the value for the variable 'foo' is retrieved and printed. In version 2, the variable '$foo' is first interpolated to give the variable name 'bar' whose value is then retrieved and printed.
The use of the optional '$' has never been strongly recommended, but to assist in backwards compatibility with any version 1 templates that may rely on this ``feature'', the V1DOLLAR option can be set to 1 (default: 0) to revert the behaviour and have leading '$' characters ignored.
my $template = Template->new({
V1DOLLAR => 1,
});
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.
This is an implementation of the 'Chain of Responsibility' design pattern as described in ``Design Patterns'', Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides), Addision-Wesley, ISBN 0-201-63361-2, page 223 .
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',
});
fetch() method) which are responsible
for loading and instantiating template plugin objects. The
Template::Content 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,
});
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.
my $template = Template->new({
SERVICE => MyOrg::Template::Service->new({ ... }),
});
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({ ... }),
});
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. These may also be specified as the PRE_DEFINE option for backwards compatibility with version 1.
my $template = Template->new({
VARIABLES => {
id => 'abw',
name => 'Andy Wardley',
},
};
my $template = Template->new({
PARSER => MyOrg::Template::Parser->new({ ... }),
});
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();
});
Andy Wardley <abw@andywardley.com>
http://www.andywardley.com/|http://www.andywardley.com/
Template Toolkit version 2.10, released on 24 July 2003.
Copyright (C) 1996-2003 Andy Wardley. All Rights Reserved. Copyright (C) 1998-2002 Canon Research Centre Europe Ltd.
This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
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Template::Manual::Config - Configuration options |