Template::Stash(3) User Contributed Perl Documentation Template::Stash(3)NAMETemplate::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 evlauted 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|Template::Manual::Config#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) 1996-2012 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
perl v5.14.3 2012-01-25 Template::Stash(3)
