ControlFlowMixin

class support.control_flow.ControlFlowMixin

Bases: object

Mixin class for controlling when and until when functions are called. Examples assume this class has been mixed into some child class:

MixedIn(ControlFlowMixin):
    pass

mixed_in = MixedIn()

tz

timezone. Defaults to UTC

Type

pytz.timezone

Attributes Summary

tz

Methods Summary

at(when)	Created a _DelayedCall instance that will run or loop at a specified time.
next_up()	Return an empty _DelayedCall instance.
now()	returns timezone aware datetime object
until([cond])	Run some generator until some condition, or list of conditions is met.

Attributes Documentation

tz = <UTC>

Methods Documentation

at(when)

Created a _DelayedCall instance that will run or loop at a specified time.

Examples:

def runner():
    yield

for e in mixed_in.at(
    MixedIn.now() + datetime.timedelta(seconds=5)).run(runner):
    yield e

Parameters

when (datetime.datetime) – timezone aware datetime object indicating when to _DelayedCall methods.

Returns

_DelayedCall

next_up()

Return an empty _DelayedCall instance.

classmethod now()

Returns

timezone aware datetime object

Return type

datetime.datetime

until(cond=None)

Run some generator until some condition, or list of conditions is met.

Examples:

Say we have some function runner defined as follows:

def runner():
    print("runner called")
    yield

We can use until in a variety of ways:

import datetime
import random

# run until runner is complete, or for next 5 seconds,
# which ever comes first
for e in mixed_in.until(
    MixedIn.now() + datetime.timedelta(seconds=5)).run(runner):
    yield e

# run until the following function evaluates to True

def condition_factory():
    def condition():
        rand = random.random()
        if rand > 0.5:
            return True
        return False
    return condition

for e in mixed_in.until(condition_factory()).run(runner):
    yield e

# we can pass a list of conditions if we want:

for e in mixed_in.until(
    [condition_factory(), condition_factory()]).run(runner):
    yield e

Parameters

cond (list/callable/datetime.datetime) – List of callables that return booleans, a single boolean-returning callable, or a datetime.datetime object. If the latter is passed, the resulting _DelayedCall object will run, loop, or wait until the specified time.

Returns

_DelayedCall