forwardable 0.2.1

Forwardable as in Ruby's stdlib

Utility for easy object composition via delegation. Roughly ported from Ruby’s forwardable standard library.

Installation

$ pip install forwardable

Usage

The @forwardable.forwardable() decorator enables you to use def_delegator in a class definition block.

from forwardable import forwardable

@forwardable() # Note the () here, which is required.
class Foo(object):
    def_delegators('bar', ('add', '__len__'))

    def __init__(self)
        self.bar = set()

foo = Foo()
foo.add(1) # Delegates to foo.bar.add()
assert len(foo) == 1

Easy, heh?

In case you only need to delegate one method to a delegatee, just use def_delegator:

from forwardable import forwardable

@forwardable()
class Foo(object):
    def_delegator('bar', '__len__')

    def __init__(self)
        self.bar = set()

assert len(Foo()) == 0

And it should work just fine.

Less Magical Usage

If you hesitate to touch the @forwardable() injection magic, just from forwardable import def_delegator, def_delegators, use them in a class definition and you’ll be fine.

License

MIT license.