requires 0.10.3

Runtime imports and dependency utils

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?