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Cliff Stanford
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NAME

Mustache::Simple - A simple Mustache Renderer

See http://mustache.github.com/.

VERSION

This document describes Mustache::Simple version 1.3.6

SYNOPSIS

A typical Mustache template:

    my $template = <<EOT;
    Hello {{name}}
    You have just won ${{value}}!
    {{#in_ca}}
    Well, ${{taxed_value}}, after taxes.
    {{/in_ca}}
    EOT

Given the following hashref:

    my $context = {
        name => "Chris",
        value => 10000,
        taxed_value => 10000 - (10000 * 0.4),
        in_ca => 1
    };

Will produce the following:

    Hello Chris
    You have just won $10000!
    Well, $6000, after taxes.

using the following code:

    my $tache = new Mustache::Simple(
        throw => 1
    );
    my $output = $tache->render($template, $context);

DESCRIPTION

Mustache can be used for HTML, config files, source code - anything. It works by expanding tags in a template using values provided in a hash or object.

There are no if statements, else clauses, or for loops. Instead there are only tags. Some tags are replaced with a value, some nothing, and others a series of values.

This is a simple perl implementation of the Mustache rendering. It has a single class method, new() to obtain an object and a single instance method render() to convert the template and the hashref into the final output.

As of version 1.2.0, it has support for nested contexts, for the dot notation and for the implicit iterator.

As of version 1.3.0, it will accept a blessed object. For any {{item}} where the object has a method called item (as returned by $object->can), the value will be the return from the method call (with no parameters). If $object->can(item) returns undef, the object will be treated as a hash and the value looked up directly. See "MANAGING OBJECTS" below.

As of version 1.3.6, if a method call on a blessed object returns an array, a {{#item}} section will iterate over the array. This also works recursively, so a method can return an array of objects.

Rationale

I wanted a simple rendering tool for Mustache that did not require any subclassing.

METHODS

Creating a new Mustache::Simple object

new
    my $tache = new Mustache::Simple(%options)

Parameters:

path

The path from which to load templates and partials. This may be a string or a reference to an array of strings. If it is a reference, each string will be searched in order.

Default: '.'

extension

The extension to add to filenames when reading them off disk. The '.' should not be included as this will be added automatically.

Default: 'mustache'

throw

If set to a true value, Mustache::Simple will croak when there is no key in the context hash for a given tag.

Default: undef

partial

This may be set to a subroutine to be called to generate the filename or the template for a partial. If it is not set, partials will be loaded using the same parameters as render().

Default: undef

Configuration Methods

The configuration methods match the %options array thay may be passed to new().

Each option may be called with a non-false value to set the option and will return the new value. If called without a value, it will return the current value.

path()
    $tache->path('/some/new/template/path');
or
    $tache->path([ qw{/some/new/template/path .} ]);
    my $path = $tache->path;    # defaults to '.'
extension()
    $tache->extension('html');
    my $extension = $tache->extension;  # defaults to 'mustache'
throw()
    $tache->throw(1);
    my $throwing = $tache->throw;       # defaults to undef
partial()
    $tache->partial(\&resolve_partials)
    my $partial = $tache->partial       # defaults to undef

Instance methods

read_file()
    my $template = read_file('templatefile');

You will not usually need to call this directly as it's called by "render" to load the file. If it is passed a string that looks like a template (i.e. has {{ in it) it simply returns it. Similarly, if, after prepending the path and adding the suffix, it cannot load the file, it simply returns the original string.

render()
    my $context = {
        "name" => "Chris",
        "value" => 10000,
        "taxed_value" => 10000 - (10000 * 0.4),
        "in_ca" => true
    }
    my $html = $tache->render('templatefile', $context);

This is the main entry-point for rendering templates. It can be passed either a full template or path to a template file. See "read_file" for details of how the file is loaded. It must also be passed a hashref containing the main context.

In callbacks (sections like {{#this}} with a subroutine in the context), you may call render on the passed string and the current context will be remembered. For example:

    {
        name => "Willy",
        wrapped => sub {
            my $text = shift;
            chomp $text;
            return "<b>" . $tache->render($text) . "</b>\n";
        }
    }

Alternatively, you may pass in an entirely new context when calling render() from a callback.

COMPLIANCE WITH THE STANDARD

The original standard for Mustache was defined at the Mustache Manual and this version of Mustache::Simple was designed to comply with just that. Since then, the standard for Mustache seems to be defined by the Mustache Spec.

The test suite on this version skips a number of tests in the Spec, all of which relate to Decimals or White Space. It passes all the other tests. The YAML from the Spec is built into the test suite.

MANAGING OBJECTS

If a blessed object is passed in (at any level) as the context for rendering a template, Mustache::Simple will check each tag to see if it can be called as a method on the object. To achieve this, it calls can from UNIVERSAL on the object. If $object->can(tag) returns code, this code will be called (with no parameters). Otherwise, if the object is based on an underlying HASH, it will be treated as that HASH. This works well for objects with AUTOLOADed "getters".

For example:

    package Test::Mustache;

    sub new
    {
        my $class = shift;
        my %params = @_;
        bless \%params, $class;
    }

    sub name    # Ensure the name starts with a capital
    {
        my $self = shift;
        (my $name = $self->{name}) =~ s/.*/\L\u$&/;
        return $name;
    }

    sub AUTOLOAD    # generic getter / setter
    {
        my $self = shift;
        my $value = shift;
        (my $method = our $AUTOLOAD) =~ s/.*:://;
        $self->{$method} = $value if defined $value;
        return $self->{$method};
    }

    sub DESTROY { }

Using the above object as $object, {{name}} would call $object->can('name') which would return a reference to the name method and thus that method would be called as a "getter". On a call to {{address}}, $object->can would return undef and therefore $object->{address} would be used.

This is usually what you want as it avoids the call to $object->AUTOLOAD for each simple lookup. If, however, you want something different to happen, you either need to declare a "Forward Declaration" (see perlsub) or you need to override the object's can (see UNIVERSAL).

BUGS

White Space

Much of the more esoteric white-space handling specified in The Mustache Spec is not strictly adhered to in this version. Most of this will be addressed in a future version.

Because of this, the following tests from the Mustache Spec are skipped:

  • Indented Inline

  • Indented Inline Sections

  • Internal Whitespace

  • Standalone Indentation

  • Standalone Indented Lines

  • Standalone Line Endings

  • Standalone Without Newline

  • Standalone Without Previous Line

Decimal Interpolation

The spec implies that the template "{{power}} jiggawatts!" when passed { power: "1.210" } should return "1.21 jiggawatts!". I believe this to be wrong and simply a mistake in the YAML of the relevant tests or possibly in YAML::XS. I am far from being a YAML expert.

Clearly { power : 1.210 } would have the desired effect.

Because of this, all tests matching /Decimal/ have been skipped. We can just assume that Perl will do the right thing.

EXPORTS

Nothing.

SEE ALSO

Template::Mustache - a much more complex module that is designed to be subclassed for each template.

AUTHOR INFORMATION

Cliff Stanford <cliff@may.be>

SOURCE REPOSITORY

The source is maintained at a public Github repository at https://github.com/CliffS/mustache-simple. Feel free to fork it and to help me fix some of the above issues. Please leave any bugs or issues on the Issues page and I will be notified.

LICENCE AND COPYRIGHT

Copyright © 2014, Cliff Stanford <cliff@may.be>. All rights reserved.

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