MakeMethods::Template:UservContributed PerlMakeMethods::Template::Universal(3)NAMEClass::MakeMethods::Template::Universal - Meta-methods for any type of
object
SYNOPSIS
package MyObject;
use Class::MakeMethods::Template::Universal (
'no_op' => [ 'twiddle' ],
'croak' => [ 'fail', { croak_msg => 'Curses!' } ]
);
package main;
MyObject->twiddle; # Does nothing
if ( $foiled ) { MyObject->fail() } # Dies with croak_msg
DESCRIPTIONUNIVERSAL META-METHODS
The following meta-methods and behaviors are applicable across multiple
types of classes and objects.
Universal:generic
This is not a directly-invokable method type, but instead provides code
expressions for use in other method-generators.
You can use any of these features in your meta-method interfaces
without explicitly importing them.
Modifiers
· --private
Causes the method to croak if it is called from outside of the
package which originally declared it.
Note that this protection can currently be circumvented if your
class provides the method_init behavior, or another subroutine that
calls methods by name.
· --protected
Causes the method to croak if it is called from a package other
than the declaring package and its inheritors.
Note that this protection can currently be circumvented if your
class provides the method_init behavior, or another subroutine that
calls methods by name.
· --public
Cancels any previous -private or -protected declaration.
· --self_closure
Causes the method to return a function reference which is bound to
the arguments provided when it is first called.
For examples of usage, see the test scripts in t/*closure.t.
· --lvalue
Adds the ":lvalue" attribute to the subroutine declaration.
For examples of usage, see the test scripts in t/*lvalue.t.
· --warn_calls
For diagnostic purposes, call warn with the object reference,
method name, and arguments before executing the body of the method.
Behaviors
· attributes
Runtime access to method parameters.
· no_op -- See below.
· croak -- See below.
· method_init -- See below.
no_op
For each meta-method, creates a method with an empty body.
use Class::MakeMethods::Template::Universal (
'no_op' => [ 'foo bar baz' ],
);
You might want to create and use such methods to provide hooks for
subclass activity.
No interfaces or parameters supported.
croak
For each meta-method, creates a method which will croak if called.
use Class::MakeMethods::Template::Universal (
'croak' => [ 'foo bar baz' ],
);
This is intended to support the use of abstract methods, that must be
overidden in a useful subclass.
If each subclass is expected to provide an implementation of a given
method, using this abstract method will replace the generic error
message below with the clearer, more explicit error message that
follows it:
Can't locate object method "foo" via package "My::Subclass"
The "foo" method is abstract and can not be called on My::Subclass
However, note that the existence of this method will be detected by
UNIVERSAL::can(), so it is not suitable for use in optional interfaces,
for which you may wish to be able to detect whether the method is
supported or not.
The -unsupported and -prohibited interfaces provide alternate error
messages, or a custom error message can be provided using the
'croak_msg' parameter.
method_init
Creates a method that accepts a hash of key-value pairs, or a reference
to hash of such pairs. For each pair, the key is interpreted as the
name of a method to call, and the value is the argument to be passed to
that method.
Sample declaration and usage:
package MyObject;
use Class::MakeMethods::Template::Universal (
method_init => 'init',
);
...
my $object = MyObject->new()
$object->init( foo => 'Foozle', bar => 'Barbados' );
# Equivalent to:
$object->foo('Foozle');
$object->bar('Barbados');
You might want to create and use such methods to allow easy
initialization of multiple object or class parameters in a single call.
Note: including methods of this type will circumvent the protection of
"private" and "protected" methods, because it an outside caller can
cause an object to call specific methods on itself, bypassing the
privacy protection.
forward_methods
Creates a method which delegates to an object provided by another
method.
Example:
use Class::MakeMethods::Template::Universal
forward_methods => [
--target=> 'whistle', w,
[ 'x', 'y' ], { target=> 'xylophone' },
{ name=>'z', target=>'zither', target_args=>[123], method_name=>do_zed },
];
Example: The above defines that method "w" will be handled by the
calling "w" on the object returned by "whistle", whilst methods "x" and
"y" will be handled by "xylophone", and method "z" will be handled by
calling "do_zed" on the object returned by calling "zither(123)".
Interfaces:
forward (default)
Calls the method on the target object. If the target object is
missing, croaks at runtime with a message saying "Can't forward bar
because bar is empty."
delegate
Calls the method on the target object, if present. If the target
object is missing, returns nothing.
Parameters: The following additional parameters are supported:
target
Required. The name of the method that will provide the object that
will handle the operation.
target_args
Optional ref to an array of arguments to be passed to the target
method.
method_name
The name of the method to call on the handling object. Defaults to
the name of the meta-method being created.
SEE ALSO
See Class::MakeMethods for general information about this distribution.
See Class::MakeMethods::Template for information about this family of
subclasses.
perl v5.14.22004-09-0MakeMethods::Template::Universal(3)
