phpman > perldoc > Template::Stash(3pm)

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 AT 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