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 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