Dinking around with decorators

only_if.py

import time
import json
import random
from functools import wraps


def only_if(condition, args_=None, *, pass_value=False, cache=False):
    _fn = condition if callable(condition) else lambda: condition

    if args_ is None:
        args_ = tuple()
    elif not isinstance(args_, tuple):
        args_ = (args_,)

    def _only_inner(func):
        cache_should_run = _fn(*args_)

        @wraps(func)
        def wrapper(*args, **kwargs):
            if cache_should_run and cache:
                if pass_value:
                    args = (cache_should_run, *args,)
                return func(*args, **kwargs)

            should_run = _fn(*args_)

            if should_run:
                if pass_value:
                    args = (should_run, *args)
                return func(*args, **kwargs)

            # does not run

        return wrapper
    return _only_inner


def random_run():
    return random.randint(0, 3)


def check_config(path, feature):
    with open(path, 'rb') as ins_file:
        data = json.load(ins_file)
    return data.get(feature, None)


@only_if(random_run, pass_value=True, cache=False)
def test_this(v):
    return f'x {v}'


@only_if(check_config, (r'./config.json', 'feature_a'), pass_value=True, cache=True)
def test_config_read(value):
    return f'cached config {value}'


@only_if(check_config, (r'./config.json', 'feature_a'), pass_value=True)
def test_no_cache_config_read(value):
    return f'live config {value}'