Template::Stash
Author: Andy Wardley

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#### Template::Service

General purpose template processing service Up

#### Template::* Modules

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#### Template::Stash::* Modules

# Template::Stash

## Magical storage for template variables

# Contents

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# SYNOPSIS

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    use Template::Stash;

    my $stash = Template::Stash->new(\%vars);

    # get variable values
    $value = $stash->get($variable);
    $value = $stash->get(\@compound);

    # set variable value
    $stash->set($variable, $value);
    $stash->set(\@compound, $value);

    # default variable value
    $stash->set($variable, $value, 1);
    $stash->set(\@compound, $value, 1);

    # set variable values en masse
    $stash->update(\%new_vars)

    # methods for (de-)localising variables
    $stash = $stash->clone(\%new_vars);
    $stash = $stash->declone();

# DESCRIPTION

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The `Template::Stash` module defines an object class which is used to store variable values for the runtime use of the template processor. Variable values are stored internally in a hash reference (which itself is blessed to create the object) and are accessible via the get() and set() methods.

Variables may reference hash arrays, lists, subroutines and objects as well as simple values. The stash automatically performs the right magic when dealing with variables, calling code or object methods, indexing into lists, hashes, etc.

The stash has clone() and declone() methods which are used by the template processor to make temporary copies of the stash for localising changes made to variables.

# PUBLIC METHODS

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## new(\%params)

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The `new()` constructor method creates and returns a reference to a new `Template::Stash` object.

    my $stash = Template::Stash->new();

A hash reference may be passed to provide variables and values which should be used to initialise the stash.

    my $stash = Template::Stash->new({ var1 => 'value1',
                                       var2 => 'value2' });

## get($variable)

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The `get()` method retrieves the variable named by the first parameter.

    $value = $stash->get('var1');

Dotted compound variables can be retrieved by specifying the variable elements by reference to a list. Each node in the variable occupies two entries in the list. The first gives the name of the variable element, the second is a reference to a list of arguments for that element, or `0` if none.

    [% foo.bar(10).baz(20) %]

    $stash->get([ 'foo', 0, 'bar', [ 10 ], 'baz', [ 20 ] ]);

## set($variable, $value, $default)

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The `set()` method sets the variable name in the first parameter to the value specified in the second.

    $stash->set('var1', 'value1');

If the third parameter evaluates to a true value, the variable is set only if it did not have a true value before.

    $stash->set('var2', 'default_value', 1);

Dotted compound variables may be specified as per get() above.

    [% foo.bar = 30 %]

    $stash->set([ 'foo', 0, 'bar', 0 ], 30);

The magical variable '`IMPORT`' can be specified whose corresponding value should be a hash reference. The contents of the hash array are copied (i.e. imported) into the current namespace.

    # foo.bar = baz, foo.wiz = waz
    $stash->set('foo', { 'bar' => 'baz', 'wiz' => 'waz' });

    # import 'foo' into main namespace: bar = baz, wiz = waz
    $stash->set('IMPORT', $stash->get('foo'));

## clone(\%params)

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The `clone()` method creates and returns a new `Template::Stash` object which represents a localised copy of the parent stash. Variables can be freely updated in the cloned stash and when declone() is called, the original stash is returned with all its members intact and in the same state as they were before `clone()` was called.

For convenience, a hash of parameters may be passed into `clone()` which is used to update any simple variable (i.e. those that don't contain any namespace elements like `foo` and `bar` but not `foo.bar`) variables while cloning the stash. For adding and updating complex variables, the set() method should be used after calling `clone().` This will correctly resolve and/or create any necessary namespace hashes.

A cloned stash maintains a reference to the stash that it was copied from in its `_PARENT` member.

## declone()

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The `declone()` method returns the `_PARENT` reference and can be used to restore the state of a stash as described above.

# AUTHOR

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Andy Wardley <abw@wardley.org> http://wardley.org/

# COPYRIGHT

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Copyright (C) 1996-2007 Andy Wardley. All Rights Reserved.

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

# SEE ALSO

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Template, Template::Context

/modules/Template/Stash.html last modified 10:55:10 31-May-2007