multipledispatch 0.2.0

Example

>>> from multipledispatch import dispatch

>>> @dispatch(int, int)
... def add(x, y):
...     return x + y

>>> @dispatch(object, object)
... def add(x, y):
...     return "%s + %s" % (x, y)

>>> add(1, 2)
3

>>> add(1, 'hello')
'1 + hello'

What this does

• Dispatches on all non-keyword arguments

• Supports inheritance

• Supports union types, e.g. (int, float)

• Supports builtin abstract classes, e.g. Iterator, Number, ...

• Caches for fast repeated lookup

• Identifies possible ambiguities at function definition time

• Provides hints to resolve ambiguities when they occur

What this doesn’t do

• Dispatch on class methods

class Foo(object):
    @dispatch(int)
    def add(self, other):
        ...

• Vararg dispatch

@dispatch([int])
def add(*args):
    ...

• Diagonal dispatch

a = arbitrary_type()
@dispatch(a, a)
def are_same_type(x, y):
    return True

• Respect namespaces

Installation and Dependencies

multipledispatch is on the Python Package Index (PyPI):

pip install multipledispatch

or

easy_install multipledispatch

multipledispatch supports Python 2.6+ and Python 3.2+ with a common codebase. It is pure Python and requires no dependencies beyond the standard library.

It is, in short, a light weight dependency.

License

New BSD. See License.

Links

• Five-minute Multimethods in Python by Guido

• `multimethods package on PyPI <https://pypi-hypernode.com/pypi/multimethods>`__

• Clojure Protocols

• Julia methods docs

• Karpinksi notebook: *The Design Impact of Multiple Dispatch*

• Wikipedia article