NAME¶
accessors - create accessor methods in caller's package.
SYNOPSIS¶
package Foo;
use accessors qw( foo bar baz );
my $obj = bless {}, 'Foo';
# generates chaining accessors
# that you can set like this:
$obj->foo( 'hello ' )
->bar( 'world' )
->baz( "!\n" );
# you get the values by passing no params:
print $obj->foo, $obj->bar, $obj->baz;
DESCRIPTION¶
The
accessors pragma lets you create simple accessors at compile-time.
This saves you from writing them by hand, which tends to result in
cut-n-paste errors and a mess of duplicated code. It can also help you
reduce the ammount of unwanted
direct-variable access that may creep
into your codebase when you're feeling lazy.
accessors was designed
with laziness in mind.
Method-chaining accessors are generated by default. Note that you can still use
accessors::chained directly for reasons of backwards compatibility.
See accessors::classic for accessors that always return the current value if you
don't like method chaining.
GENERATED METHODS¶
accessors will generate methods that return the current object on set:
sub foo {
my $self = shift;
if (@_) { $self->{-foo} = shift; return $self; }
else { return $self->{-foo}; }
}
This way they can be
chained together.
Why prepend the dash?¶
The dash ("-") is prepended to the property name for a few reasons:
- •
- interoperability with Error.
- •
- to make it difficult to accidentally access the property directly ala:
use accessors qw( foo );
$obj->{foo}; # prevents this by mistake
$obj->foo; # when you probably meant this
(this might sound woolly, but it's easy enough to do).
- •
- syntactic sugar (this is woolly :).
You shouldn't care too much about how the property is stored anyway - if you do,
you're likely trying to do something special (and should really consider
writing the accessors out long hand), or it's simply a matter of preference in
which case you can use accessors::classic, or sub-class this module.
There is
little-to-no performace hit when using generated accessors; in
fact there is
usually a performance gain.
- •
- typically 10-30% faster than hard-coded accessors (like the above
example).
- •
- typically 1-15% slower than optimized accessors (less
readable).
- •
- typically a small performance hit at startup (accessors are created
at compile-time).
- •
- uses the same anonymous sub to reduce memory consumption (sometimes by
80%).
See the benchmark tests included with this distribution for more details.
MOTIVATION¶
The main difference between the
accessors pragma and other accessor
generators is
simplicity.
- •
- interface
use accessors qw( ... ) is as easy as it gets.
- •
- a pragma
it fits in nicely with the base pragma:
use base qw( Some::Class );
use accessors qw( foo bar baz );
and accessors get created at compile-time.
- •
- no bells and whistles
The module is extensible instead.
SUB-CLASSING¶
If you prefer a different style of accessor or you need to do something more
complicated, there's nothing to stop you from sub-classing. It should be
pretty easy. Look through accessors::classic, accessors::ro, and accessors::rw
to see how it's done.
CAVEATS¶
Classes using blessed scalarrefs, arrayrefs, etc. are not supported for sake of
simplicity. Only hashrefs are supported.
THANKS¶
Thanks to Michael G. Schwern for indirectly inspiring this module, and for his
feedback & suggestions.
Also to Paul Makepeace and David Wright for showing me faster accessors, to
chocolateboy for his contributions, the CPAN Testers for their bug reports,
and to James Duncan and people on London.pm for their feedback.
AUTHOR¶
Steve Purkis <spurkis@cpan.org>
SEE ALSO¶
accessors::classic, accessors::chained
Similar and related modules:
base, fields, Class::Accessor, Class::Struct, Class::Methodmaker,
Class::Generate, Class::Class, Class::Tangram, Object::Tiny