requires

Install: pip install requires

Decorate that lets you Require/Import dependencies at runtime.

Python dependency management can be mind bottlingly complex. Optional dependencies are pretty common. Why not require the dependency at run time if a function requires said dependency?

This package has come in handy in lambda-land where you only get 250mb (on aws)!

Usage:

# This will fail
def uno():
    return json.dumps({"a": 1, "b": 2})


try:
    uno()
except NameError as ne:
    print("Error:", ne)

Error: name 'json' is not defined

# This will not fail
import requires  # Module is callable! (checkout funkify for more info -- `pip install funkify`)


@requires("json")
def uno():
    return json.dumps({"a": 1, "b": 2})


uno()

'{"a": 1, "b": 2}'

import requires


@requires("from json import dumps")
def uno():
    return dumps({"a": 1, "b": 2})


uno()

'{"a": 1, "b": 2}'

def dos():
    return dumps({"a": 1, "b": 2})


dos()

'{"a": 1, "b": 2}'

import requires


@requires(_from="json", _import="dumps")
def dos():
    return dumps({"a": 1, "b": 2})


dos()

'{"a": 1, "b": 2}'

import requires


@requires(_import="rapidjson", pip="python-rapidjson", conda_forge="python-rapidjson")
def tres():
    return rapidjson.dumps({"a": 1, "b": 2})


tres()  # Will err if not install with where to install instructions

'{"a":1,"b":2}'

# should error
def quatro():
    return path.join("a", "b")


try:
    quatro()
except NameError as ne:
    print("ERROR:", ne)

ERROR: name 'path' is not defined

from requires import Requirement

os_path_req = Requirement(_import="path", _from="os")


@os_path_req
def quatro():
    return path.join("a", "b")


assert isinstance(quatro(), str)

Enforcing requirements

import requires

try:
    import alibrary
except ModuleNotFoundError:
    requirement = requires.Requirement(
        _import="alibrary",
        pip=True,
        conda_forge="alibrary-conda-listing",
        details="Install details",
    )
try:
    requirement.raise_error()
except requires.RequirementError as err:
    print("ERROR:")
    print(err)

ERROR:
Module/Package(s) not found/installed; could not import: `import alibrary`
    pip install alibrary
    conda install -c conda-forge alibrary-conda-listing
    Install details

Less verbose version:

import requires

try:
    import alibrary
except ModuleNotFoundError:
    requires.Requirement(
        _import='alibrary',
        pip=True,
        conda_forge='alibrary-conda-listing',
        details="Install details"
    ).raise_error()

Future ideas?

Adding support for requiring particular package versions?
Auto install?
Allow non pip/conda/conda-forge locations?

Release files for requires 0.12.1

For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.

Source distribution (sdist)

Source distribution for requires 0.12.1
File	Size	Uploaded
requires-0.12.1.tar.gz	8.8 kB	Oct 15, 2025	Details

Built distribution (wheel)

Table of built distributions (wheels) for requires 0.12.1
File	Interpreter	ABI	Platform	Reset
requires-0.12.1-py3-none-any.whl 10.0 kB Oct 15, 2025	Python 3	none	any	Details

Total release size: 18.8 kB

Release files / requires-0.12.1.tar.gz

Download URL	requires-0.12.1.tar.gz
Size	8.8 kB
Tags	Source
SHA-256 checksum How to use checksums	`e05a3bfbeadbf14429ce21fd2111dc36c0aca060cbe549bb6f5f010ac0bf9bb2`
BLAKE2b-256 checksum How to use checksums	`9669d04c7f4b7cf7d17086dfcc711f9fe7ec7bfaafdf0011ae4a7605ce6672b6`
Upload date	Oct 15, 2025
Uploaded using Trusted Publishing? What is trusted publishing?	No
Uploaded via	`uv/0.9.1`

Release files / requires-0.12.1-py3-none-any.whl

Download URL	requires-0.12.1-py3-none-any.whl
Size	10.0 kB
Tags	Python 3
SHA-256 checksum How to use checksums	`7c8734a810e362bd4fe77d112355e8f6f069b67376dbeeab6b2731f56367068c`
BLAKE2b-256 checksum How to use checksums	`0a6249d256dbad857672a4b1baad7bf43c3e4e863bb720c395a9b55aaca390f6`
Upload date	Oct 15, 2025
Uploaded using Trusted Publishing? What is trusted publishing?	No
Uploaded via	`uv/0.9.1`