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NAME

Plate - Fast templating engine with support for embedded Perl

SYNOPSIS

use Plate;

my $plate = Plate->new(
    path        => '/path/to/plate/files/',
    cache_path  => '/tmp/cache/',
    auto_filter => 'trim',
);

$plate->set(filters => { html => \&HTML::Escape::escape_html });
$plate->set(filters => { trim => sub { $_[0] =~ s/^\s+|\s+$//gr } });

# Render /path/to/plate/files/hello.plate cached as /tmp/cache/hello.pl
my $output = $plate->serve('hello');
print $output;

DESCRIPTION

Plate is a very fast, efficient and full-featured templating engine.

Inspired by HTML::Mason and Tenjin, the goal of this templating engine is speed and functionality. It has no non-core dependencies, is a compact size and supports embedded Perl.

Features include preprocessing templates, caching compiled templates, variable escaping/filtering, localised global variables. Templates can also include other templates, with optional content and even define or override templates & filters locally.

All templates have strict, warnings, utf8 and Perl 5.20 features enabled.

Example

Here is an example template for a letter stored in the file: letter.plate

% my($title, $surname) = @_;
Dear <% $title %> <% $surname %>,

<& _ &>

    Kind Regards,

    E. X. Ample

Another template could include this template, Eg: job.plate

<&| letter, 'Dr.', 'No' &>\
In response to the recently advertised position, please
consider my résumé in your search for a professional sidekick.
</&>

Serving the job.plate template will result in the following output:

Dear Dr. No,

In response to the recent advertised position, please
consider my résumé in your search for a professional sidekick.

        Kind Regards,

        E. X. Ample

Here is the code to render this output:

use Plate;

my $plate = Plate->new;
my $output = $plate->serve('job');

Markup

Variables

<% $var %>
<% $unescaped |%>
<% $filtered |trim |html %>

Variables are interpolated into the output and optionally filtered (escaped). Filters are listed in the order to be applied preceded by a | character. If no filter is given as in the first example, then the default filter is applied. To explicitly avoid the default filter use the empty string as a filter.

Statements

% my $user = db_lookup(user => 'bob');
% for my $var (@list) {

Lines that start with a % character are treated as Perl statements.

Comments

%# Comment line
<% # inline comment %>
<%#
    Multi-line
    comment
%>

Perl blocks

<%perl>
...
</%perl>

Perl code can also be wrapped in a perl block.

Newlines

Newline characters can be escaped with a backslash, Eg:

% for my $var ('a' .. 'c') {
<% $var %>\
% }

This will result in the output abc, all on one line.

Include other templates

<& header, 'My Title' &>
...
<& footer &>

A template can include other templates with optional arguments.

Include other templates with provided content

<&| paragraph &>
This content is passed to the "paragraph" template.
</&>

Plain text, <&| bold &>bold text</&>, plain text.

An included template can have its own content passed in.

Content

<& _ &>

A template can be served with content. This markup will insert the content provided, if any.

Def blocks

<%def copyright>
Copyright © <% $_[0] %>
</%def>

<& copyright, 2018 &>

Local templates can be defined in a template. They will override existing templates until the end of the template or block.

Filter blocks

<%filter one_line>
<% $_[0] =~ tr/\n/ / |%>
</%filter>

<%filter bold>
<b><& _ &></b>
</%filter>

<% "Single\nLine\nOnly" |one_line |bold %>

Local filters can also be defined in a template. They will override existing filters until the end of the template or block. The text to be filtered will be passed in as the only argument and also as content.

SUBROUTINES/METHODS

new

my $plate = Plate->new(%options);

Creates a new Plate engine with the options provided.

Options (with their defaults) are:

  • auto_filter => 'html'

    The name of the default filter to use for template variables when no filter is specified, <% ... %>. The built-in default filter is a very basic HTML filter. Set this to undef to disable the default filter.

    To prevent the default filter being used for just a single variable, just set the filter to an empty string. Eg: <% $unfiltered |%>

  • cache_code => 1

    If set to a true value, the engine will cache compiled template code in memory. This vastly improves performance at the expense of some memory.

  • cache_path => undef

    Set this to a directory to store compiled templates on the filesystem. If the directory does not exist, it will attempt to create it using the umask setting.

  • cache_suffix => '.pl'

    Compiled templates stored on the filesystem will have this suffix appended.

  • chomp => 1

    If set to a true value (the default), the final newline in every template will be removed.

  • encoding => 'UTF-8'

    Set this to the encoding of your template files.

  • filters => { html => \&_basic_html_filter }

    A hash of filters to set for use in templates. The key is the name of the filter, and the value is the CODE ref, subroutine name or undef. The subroutine will be given one argument (the content to filter) as a string, and must return the filtered string. To remove a filter pass undef as it's value.

    To remove all filters pass undef instead of a HASH ref.

  • keep_undef => undef

    If set to a false value (the default), then variables and calls that return undef are converted to an empty string.

  • max_call_depth => 99

    This sets the maximum call depth to prevent infinite recursion.

  • package => 'Plate::Template'

    The package name that templates are compiled and run in.

  • path => ''

    The path to the templates on the filesystem. An empty string (the default) refers to the current directory. If set to undef then the filesystem will not be searched, only cached templates will be served.

  • static => undef

    If set to a false value (the default), the engine will reload and recompile templates whenever files are modified.

    If set to a true value, file modification will not be checked nor will templates be reloaded. While this improves performance in production, it is not recommended in development.

  • suffix => '.plate'

    The suffix appended to template names when searching on the filesystem.

  • umask => 077

    The umask used when creating cache files and directories.

  • vars => {}

    A hash of vars to set for use in templates. This will define new local variables to be imported into the templating package when compiling and running templates. Values to be imported must be unblessed references. If the value is a blessed object or not a reference it will be imported as a constant into the templating package. To remove a var pass undef as it's value.

    To remove all vars pass undef instead of a HASH ref.

    All templates will have access to these variables, subroutines and constants even under use strict.

serve

my $output = $plate->serve($template_name, @arguments);

Renders a template. The @arguments will be passed to the template as @_.

serve_with

my $output = $plate->serve_with($content, $template_name, @arguments);

Renders a template with the provided content.

The content can be passed in one of three ways. If $content is a string then it is the name of a template to serve. If $content is a SCALAR ref then it is the contents of a template to be compiled and served. $content may also be a CODE ref which should return the content directly.

content

% my $content = &Plate::content;

Used from within a template to return the content passed to that template.

has_content

% if (Plate::has_content) { ...

Used from within a template to determine if that template was called with content.

define

$plate->define($template_name => $content);

This will cache a template in memory. The $content is the contents of a template (as a string) to be compiled or a CODE ref.

This is useful if you need to use templates that are not stored on the file system, for example from a database or a custom subroutine.

undefine

$plate->undefine;
$plate->undefine($template_name);

This will delete a previously cached template, or all templates if the name is undef.

does_exist

my $exists = $plate->does_exist($template_name);

% my $exists = Plate::does_exist($template_name);

Returns true if a template by that name is cached or exists on the filesystem. No attempt will be made to compile the template. The second invocation only works from within a template.

can_serve

my $ok = $plate->can_serve($template);

% my $ok = Plate::can_serve($template);

Returns true if the template can be served (compiles successfully), otherwise it sets $@ to the reason for failure. If $template is a string then it is the name of a template to compile. If $template is a SCALAR ref then it is the contents of a template to be compiled. The second invocation only works from within a template.

filter

$text = $plate->filter($text, 'html', 'bold');

% $text = Plate::filter($text, 'trim');

Filters the text using the named filters and returns the result. The second invocation only works from within a template.

set

$plate->set(%options);

Set the options for this Plate engine. Options are the same as those for "new".

AUTHOR

Vernon Lyon <[email protected]>

BUGS

Please report any bugs or feature requests on GitHub issues.

SOURCE

The source code is hosted on GitHub. Feel free to fork the repository and submit pull requests!

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc Plate

You can also read the documentation online on metacpan.

COPYRIGHT AND LICENSE

Copyright (C) 2018, Vernon Lyon.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.