Registry / serialization / singledispatch

singledispatch

library4.1.2pypypi✓ verified 23d ago

The `singledispatch` library provides a standalone implementation of the `functools.singledispatch` decorator, which allows for generic functions to have different behaviors based on the type of their first argument. Originally a backport for older Python versions, the PyPI package currently targets Python 3.9+ and is actively maintained with regular releases, as evidenced by recent version updates.

serialization

pip install singledispatch

github ↗package ↗

INSTALL

IMPORT

SIG · SINGLEDISPATCH

singledispatch

serializationpythonv4.1.2

Install

1.5s avg

Import

—

Disk

16MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v4.1.2 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.000s · 17.8MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 1.5s · import 0.000s · 18MB

16MB installed

● package 16MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

singledispatch

✓ from singledispatch import singledispatch

✗ from functools import singledispatch

While `functools.singledispatch` is built into Python 3.4+, this package provides a standalone implementation. If you install and use the `singledispatch` package, you should import from it directly to ensure you are using its version.

singledispatchmethod

✓ from singledispatch import singledispatchmethod

✗ from functools import singledispatchmethod

`singledispatchmethod` was added to `functools` in Python 3.8. If targeting Python versions prior to 3.8 (though the `singledispatch` package itself now requires Python 3.9+), or if using this package's specific implementation, import from `singledispatch` directly.

This example demonstrates how to create a single-dispatch generic function using the `@singledispatch` decorator. It defines a default implementation and then registers specific implementations for `int` and `list` types. When called, the appropriate function is dispatched based on the type of the first argument.

from singledispatch import singledispatch @singledispatch def process_data(arg): """Default implementation for process_data""" return f"Processing generic data: {arg}" @process_data.register(int) def _(arg): """Process integer data""" return f"Processing integer: {arg * 2}" @process_data.register(list) def _(arg): """Process list data""" return f"Processing list: {', '.join(map(str, arg))}" print(process_data("hello")) print(process_data(10)) print(process_data([1, 2, 3])) print(process_data(3.14))

Debug

Known issues

gotchaPotential confusion with `functools.singledispatch` which is part of Python's standard library since Python 3.4. If you are using Python 3.4 or newer, `functools.singledispatch` is generally preferred unless you specifically need the `singledispatch` package's independent implementation or its associated utilities.

fix

For new projects on Python 3.4+, consider using `from functools import singledispatch`. If you specifically need this package, ensure you import from `singledispatch`.

affects: All versions

breakingVersion 4.0.0 dropped support for Python 3.8, now requiring Python 3.9 or later. This is a significant breaking change for environments still using Python 3.8.

fix

Upgrade your Python environment to 3.9+ or pin `singledispatch` to a version older than 4.0.0 (e.g., `~=3.7`) if you need to support Python 3.8.

affects: 4.0.0 and later

gotchaThe `singledispatch` decorator, by its nature, dispatches solely based on the *type of the first argument*. It does not support multiple dispatch (dispatching on multiple arguments) or dispatching based on keyword arguments.

fix

If you require dispatching on multiple arguments or keyword arguments, you will need to implement a custom solution or use a third-party library designed for multiple dispatch.

affects: All versions

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'singledispatch'

The `singledispatch` package has not been installed in the current Python environment.

fix

pip install singledispatch

TypeError: 'module' object is not callable

The `singledispatch` module was imported directly, and then the module object was incorrectly used as a decorator.

fix

from singledispatch import singledispatch

AttributeError: 'function' object has no attribute 'register'

The `.register()` method was called on a regular Python function that had not been decorated with `@singledispatch`.

fix

from singledispatch import singledispatch

@singledispatch
def my_function(arg):
    # Default implementation
    pass

@my_function.register(int)
def _(arg: int):
    return arg + 1

TypeError: singledispatch expects a callable as its first argument

The `singledispatch` decorator or function was applied to, or passed, a non-callable object.

fix

from singledispatch import singledispatch

@singledispatch
def my_function(arg):
    # This is a callable function
    pass

Upgrade

Version history

4.1.2latest on PyPI · released May 14, 2025

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Dependencies

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Agent activity

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Resources

githubhttps://github.com/jaraco/singledispatch ↗

packagehttps://pypi.org/project/singledispatch/ ↗