Class::MethodMaker::EnUser(Contributed Perl DocumClass::MethodMaker::Engine(3)NAMEClass::MethodMaker::Engine - The parameter passing, method installation
& non-data-structure methods of Class::MethodMaker.
SYNOPSIS
This class is for internal implementation only. It is not a public
API.
The non-data-structure methods do form part of the public API, but not
called directly: rather, called through the "use"/"import" interface,
as for data-structure methods.
The Class::MethodMaker Method Installation Engine
import
This performs argument parsing ready for calling create_methods. In
particular, this is the point at which v1 & v2 calls are distinguished.
This is implicitly called as part of a "use" statement:
use Class::MethodMaker
[ scalar => [qw/ foo bar baz /],
new => [qw/ new /] ,
];
is equivalent to
Class::MethodMaker->import([scalar => [qw/ foo bar baz /],
new => [qw/ new /] ,
]);
See perldoc -f use for details of this equivalence.
The methods created are installed into the class calling the import -
or more accurately, the first class up the calling stack that is not
"Class::MethodMaker" or a subclass thereof.
SYNOPSIS
Class::MethodMaker->import([scalar => [+{ -type => 'File::Stat',
-forward => [qw/ mode size /],
'*_foo' => '*_fig',
'*_gop' => undef,
'*_bar' => '*_bar',
'*_hal' => '*_sal',
},
qw/ -static bob /,
]
]);
parse_options
Parse the arguments given to import and call create_methods
appropriately. See main text for options syntax.
SYNOPSIS
Class::MethodMaker->parse_options('TargetClass',
[scalar =>
[{ -type => 'File::stat',
-forward => [qw/ mode
size /],
'*_foo' => '*_fig',
'*_gop' => undef,
'*_bar' => '*_bar',
'*_hal' => '*_sal',
},
qw( -static bob ),
]])},
Class::MethodMaker->parse_options('TargetClass2',
[scalar =>
['baz',
{ -type => 'File::stat',
-forward => [qw/ mode
size /],
'*_foo' => '*_fog',
'*_bar' => '*_bar',
'*_hal' => '*_sal',
},
qw( -static bob ),
]],
+{ -type => 'Math::BigInt', },
+{'*_foo' => '*_fig',
'*_gop' => undef,},
)},
ARGUMENTS
target_class
The class into which to install components
args
The arguments to parse, as a single arrayref.
options
A hashref of options to apply to all components created by this
call (subject to overriding by explicit option calls).
renames
A hashref of renames to apply to all components created by this
call (subject to overriding by explicit rename calls).
create_methods
Add methods to a class. Methods for multiple components may be added
this way, but create_methods handles only one set of options.
parse_options is responsible for sorting which options to apply to
which components, and calling create_methods appropriately.
SYNOPSIS
Class::MethodMaker->create_methods($target_class,
scalar => bob,
+{ static => 1,
type => 'File::Stat',
forward => [qw/ mode size /], },
+{ '*_foo' => '*_fig',
'*_gop' => undef,
'*_bar' => '*_bar',
'*_hal' => '*_sal', }
);
ARGUMENTS
targetclass
The class to add methods to.
type
The basic data structure to use for the component, e.g.,
"scalar".
compname
Component name. The name must be a valid identifier, i.e., a
continguous non-empty string of word ("\w") characters, of
which the first may not be a digit.
options
A hashref. Some options ("static", "type", "default",
"default_ctor") are handled by the auto-extender. These will
be invoked if the name is present as a key and the value is
true. Any other options are passed through to the method in
question. The options should be named as-is; no leading hyphen
should be applied (i.e., use "{static => 1}" not "{-static =>
1}").
renames
A list of customer renames. It is a hashref from method name
to rename. The method name is the generic name (i.e.,
featuring a "*" to replace with the component name). The
rename is the value to rename with. It may itself contain a
"*" to replace with the component name. If rename is undef,
the method is not installed. For methods that would not be
installed by default, use a rename value that is the same as
the method name.
So, if a type would normally install methods
'*_foo', '*_gop', '*_tom'
and optionally installs (but not by default)
'*_bar', '*_wiz', '*_hal'
using a renames value of
{ '*_foo' => '*_fig',
'*_gop' => undef,
'*_bar' => '*_bar',
'*_hal' => '*_sal',
}
with a component name of "xx", then *_foo is installed as
"xx_fig", *_bar is installed as "xx_bar", *_wiz is not
installed, *_hal is installed as "xx_sal", *_gop is not
installed, and *_tom is installed as "xx_tom".
The value may actually be an arrayref, in which case the
function may be called by any of the multiple names specified.
install_methods
SYNOPSIS
Class::MethodMaker->install_methods
($classname, { incr => sub { $i++ },
decr => sub { $i-- },
}
);
ARGUMENTS
target
The class into which the methods are to be installed
methods
The methods to install, as a hashref. Keys are the method
names; values are the methods themselves, as code refs.
Non-data-structure components
new
use Class::MethodMaker
[ new => 'new' ];
Creates a basic constructor.
Takes a single string or a reference to an array of strings as its
argument. For each string creates a simple method that creates and
returns an object of the appropriate class.
The generated method may be called as a class method, as usual, or as
in instance method, in which case a new object of the same class as the
instance will be created.
Options
-hash
The contructor will accept as arguments a list of pairs, from
component name to initial value. For each pair, the named
component is initialized by calling the method of the same name
with the given value. E.g.,
package MyClass;
use Class::MethodMaker
[ new => [qw/ -hash new /],
scalar => [qw/ b c /],
];
sub d {
my $self = shift;
$self->{d} = $_[0]
if @_;
return $self->{d};
}
package main;
# The statement below implicitly calls
# $m->b(1); $m->c(2); $m->d(3)
# on the newly constructed m.
my $m = MyClass->new(b => 1, c => 2, d => 3);
Note that this can also call user-supplied methods that have the
name of the component.
Instead of a list of pairs, a single hashref may also be passed,
which will be expanded appropriately. So the above is equivalent
to:
my $m = MyClass->new({ b => 1, c => 2, d => 3 });
Advanced Users: Class::MethodMaker method renaming is taken into
account, so even if the "*" method is renamed or removed, this will
still work.
-init
This option causes the new method to call an initializor method.
The method is called "init" (original, eh?) by default, but the
option may be given an alternative value. The init method is
passed any arguments that were passed to the constructor, but the
method is invoked on the newly constructed instance.
use Class::MethodMaker
[ new => [qw/ -init new1 /, { -init => 'bob' } => 'init2' ]];
Constructing with new1 involves an implicit call to "init", whilst
constructing with new2 involves an implicit call to "bob" (instead
of "init").
It is the responsiblity of the user to ensure that an "init" method
(or whatever name) is defined.
-singleton
Creates a basic constructor which only ever returns a single
instance of the class: i.e., after the first call, repeated calls
to this constructor return the same instance. Note that the
instance is instantiated at the time of the first call, not before.
abstract
use Class::MethodMaker
[ abstract => [ qw / foo bar baz / ] ];
This creates a number of methods that will die if called. This is
intended to support the use of abstract methods, that must be overidden
in a useful subclass.
copy
use Class::MethodMaker
[ copy => [qw/ shallow -deep deep /] ];
This creates method that produce a copy of self. The copy is a by
default a shallow copy; any references will be shared by the instance
upon which the method is called and the returned newborn. One option
is taken, "-deep", which causes the method to create deep copies
instead (i.e., references are copied recursively).
Implementation Note:
Deep copies are performed using the "Storable" module if available,
else "Data::Dumper". The "Storable" module is liable to be much
quicker. However, this implementation note is not an API
specification: the implementation details are open to change in a
future version as faster/better ways of performing a deep copy become
available.
Note that deep copying does not currently support the copying of
coderefs, ties or XS-based objects.
AUTHOR
Martyn J. Pearce <fluffy@cpan.org>
perl v5.14.1 2011-04-16 Class::MethodMaker::Engine(3)
