# Template::Stash - phpMan

## NAME
    [Template::Stash] - Magical storage for template variables

## SYNOPSIS
        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
    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
  new(\%params)
    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)
    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)
    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'));

  update($variables)
    This method can be used to set or update several variables in one go.

        $stash->update({
            foo => 10,
            bar => 20,
        });

  getref($variable)
    This undocumented feature returns a closure which can be called to get
    the value of a variable. It is used to implement variable references
    which are evaluated lazily.

        [% x = \foo.bar.baz %]          # x is a reference to foo.bar.baz
        [% x %]                         # evalautes foo.bar.baz

  clone(\%params)
    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()
    The "declone()" method returns the "_PARENT" reference and can be used
    to restore the state of a stash as described above.

  define_vmethod($type, $name, $code)
    This method can be used to define new virtual methods. The first
    argument should be either "scalar" or "item" to define scalar virtual
    method, "hash" to define hash virtual methods, or either "array" or
    "list" for list virtual methods. The second argument should be the name
    of the new method. The third argument should be a reference to a
    subroutine implementing the method. The data item on which the virtual
    method is called is passed to the subroutine as the first argument.

        $stash->define_vmethod(
            item => ucfirst => sub {
                my $text = shift;
                return ucfirst $text
            }
        );

## INTERNAL METHODS
  dotop($root, $item, \@args, $lvalue)
    This is the core "dot" operation method which evaluates elements of
    variables against their root.

  undefined($ident, $args)
    This method is called when get() encounters an undefined value. If the
    STRICT option is in effect then it will throw an exception indicating
    the use of an undefined value. Otherwise it will silently return an
    empty string.

    The method can be redefined in a subclass to implement alternate
    handling of undefined values.

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

## COPYRIGHT
    Copyright (C) 1996-2013 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
    Template, [Template::Context]