ctxs - extra helpers for python "with ..."

The with statement available in python makes it possible to add context and cleanup to resources, which is useful when working with shared resources that needs to be released afterwards.

This adds some extra tools to make usage easier.

ContextObject

When working with multiple contexts at the same time, it is possible to use multiple context managers in the same with statement:

with ResourceA() as a, ResourceB() as b:
    a.do_something()
    b.do_something()

But if something needs to be added to the scope later, or dynamically add resources to the same context, it is not possible.

ContextObject() managed the context, and new resources can be added later, using the <<-operator.

The above statement is equivalent to:

from ctxs import ContextObject

with ContextObject() as ctx:
    a = ctx << ResourceA()
    b = ctx << ResourceB()

    a.do_something()
    b.do_something()

with the addition that resources can be added later, and dynamically.

ContextThread

threading adds the possibilty to create threads easily. However, synchronizing execution is still based upon function calls to the thread object.

In many cases, some thread should be running only within the scope of a certain block. For example, a temporary server thread only available when a system is in a certain state.

ContextThread makes it possible to create a thread that is running within a given context, with or without ContextObject above.

To create a ContextThread, extend the ContextThread and implement the run() function, which is executed when the thread enters the context.

Within the context, the self.is_running is True while running, and when exiting the context, it will be set to False.

from ctxs import ContextThread
import time

class MyThread(ContextThread):
    def __init__(self) -> None:
        pass

    def run(self) -> None:
        while self.is_running:
            print("Tick...")
            time.sleep(1.0)

# Create and run in parallel
with MyThread():
    for i in range(10):
        time.sleep(0.7)
        print("Tock...")

print("Has it stopped?")
time.sleep(4.0)
print("Who knows...")

Installation

ctxs is available on pypi

To install:

pip install ctxs

Feedback

The goal of this library is to keep as clean as possible, while still complement the builtin behaviour.

If you have any thoughts about what it should added.

Roadmap / Ideas

• ContextObject initialized by collections, to make it possible to enter a set/list/dict of context managers.
• Add ContextObject to other objects, to support nested contexts. For example a server (implemented as a ContextThread) can spawn it's client threads within the parents context.