1. Aric Coady
  2. multimethod

Overview

About Multimethod

Multiple argument dispatching.

Call multimethod on a variable number of types. It returns a decorator which finds the multimethod of the same name, creating it if necessary, and adds that function to it.

@multimethod(*types)
def func(*args):
   pass

func is now a multimethod which will delegate to the above function, when called with arguments of the specified types. If an exact match can't be found, the next closest method is called (and cached).

If strict mode is enabled, and there are multiple candidate methods, a TypeError is raised. A function can have more than one multimethod decorator. Keyword arguments can be used when calling, but won't affect the dispatching.

The functools.singledispatch style syntax introduced in Python 3.4 is also supported.

@multidispatch
def func(*args):
   pass

@func.register(*types)
def _(*args):
   pass

See tests for more example usage.

Installation

Standard installation from pypi or local download.

$ pip install multimethod
$ python setup.py install

Dependencies

Python 2.7 or 3.3+.

Tests

100% branch coverage.

$ py.test [--cov]

Changes

0.5

  • Optimized dispatching
  • Support for functools.singledispatch syntax

0.4

  • Dispatch on Python 3 annotations