template::stash::context(3pm) [debian man page]

Template::Stash::Context(3pm)				User Contributed Perl Documentation			     Template::Stash::Context(3pm)

NAME

       Template::Stash::Context - Experimetal stash allowing list/scalar context definition

SYNOPSIS

	   use Template;
	   use Template::Stash::Context;

	   my $stash = Template::Stash::Context->new(\%vars);
	   my $tt2   = Template->new({ STASH => $stash });

DESCRIPTION

       This is an alternate stash object which includes a patch from Craig Barratt to implement various new virtual methods to allow dotted
       template variable to denote if object methods and subroutines should be called in scalar or list context.  It adds a little overhead to
       each stash call and I'm a little wary of applying that to the core default stash without investigating the effects first. So for now, it's
       implemented as a separate stash module which will allow us to test it out, benchmark it and switch it in or out as we require.

       This is what Craig has to say about it:

       Here's a better set of features for the core.  Attached is a new version of Stash.pm (based on TT2.02) that:

       * supports the special op "scalar" that forces scalar context on function calls, eg:

	   cgi.param("foo").scalar

       calls cgi.param("foo") in scalar context (unlike my wimpy scalar op from last night).  Array context is the default.

       With non-function operands, scalar behaves like the perl version (eg: no-op for scalar, size for arrays, etc).

       * supports the special op "ref" that behaves like the perl ref.	If applied to a function the function is not called.  Eg:

	   cgi.param("foo").ref

       does *not* call cgi.param and evaluates to "CODE".  Similarly, HASH.ref, ARRAY.ref return what you expect.

       * adds a new scalar and list op called "array" that is a no-op for arrays and promotes scalars to one-element arrays.

       * allows scalar ops to be applied to arrays and hashes in place, eg: ARRAY.repeat(3) repeats each element in place.

       * allows list ops to be applied to scalars by promoting the scalars to one-element arrays (like an implicit "array").  So you can do things
       like SCALAR.size, SCALAR.join and get a useful result.

       This also means you can now use x.0 to safely get the first element whether x is an array or scalar.

       The new Stash.pm passes the TT2.02 test suite.  But I haven't tested the new features very much.  One nagging implementation problem is
       that the "scalar" and "ref" ops have higher precedence than user variable names.

AUTHOR

       Andy Wardley <abw@wardley.org>

       <http://wardley.org/>

VERSION

       1.63, distributed as part of the Template Toolkit version 2.19, released on 27 April 2007.

COPYRIGHT

	 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

       Template::Stash

perl v5.14.2							    2011-12-20					     Template::Stash::Context(3pm)

Template::Stash(3)					User Contributed Perl Documentation					Template::Stash(3)

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

perl v5.16.3							    2012-01-25							Template::Stash(3)