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Python 201 - Interactively Learn Advanced Concepts in Python 3

Functools: functools.singledispatch

Explore how to use the functools singledispatch decorator in Python to create generic functions that dispatch based on the first argument's type. Understand how to register handlers for various types and handle unsupported types effectively.

We'll cover the following...

Overview of singledispatch module

Python recently added partial support for function overloading in Python 3.4. They did this by adding a neat little decorator to the functools module called singledispatch. This decorator will transform our regular function into a single dispatch generic function. Note however that singledispatch only happens based on the first argument’s type.

Simple example of singledispatch()

Let’s take a look at an example to see how this works!

Python 3.5
from functools import singledispatch
@singledispatch
def add(a, b):
    raise NotImplementedError('Unsupported type')
@add.register(int)
def _(a, b):
    print("First argument is of type ", type(a))
    print(a + b)
@add.register(str)
def _(a, b):
    print("First argument is of type ", type(a))
    print(a + b)
@add.register(list)
def _(a, b):
    print("First argument is of type ", type(a))
    print(a + b)
if __name__ == '__main__':
    add(1, 2)
    add('Python', 'Programming')
    add([1, 2, 3], [5, 6, 7])

Here we import ...