async-class

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async-class

Adding abillity to write classes with awaitable initialization function.

.. contents:: Table of contents

Usage example

.. code:: python :name: test_simple

import asyncio
from async_class import AsyncClass, AsyncObject, task, link


class MyAsyncClass(AsyncClass):
     async def __ainit__(self):
          # Do async staff here
          pass


class MainClass(AsyncObject):
     async def __ainit__(self):
          # Do async staff here
          pass

     async def __adel__(self):
          """ This method will be called when object will be closed """
          pass


class RelatedClass(AsyncObject):
     async def __ainit__(self, parent: MainClass):
          link(self, parent)


async def main():
     instance = await MyAsyncClass()
     print(instance)

     main_instance = await MainClass()
     related_instance = await RelatedClass(main_instance)

     assert not main_instance.is_closed
     assert not related_instance.is_closed

     await main_instance.close()
     assert main_instance.is_closed

     # will be closed because linked to closed main_instance
     assert related_instance.is_closed

asyncio.run(main())

Documentation

Async objects might be created when no one event loop has been running. self.loop property is lazily evaluated.

Module provides useful abstractions for writing async code.

Objects inherited from AsyncClass might have their own __init__ method, but it strictly not recommend.

Class AsyncClass

Is a base wrapper with metaclass has no TaskStore instance and additional methods like self.create_task and self.create_future.

This class just solves the initialization problem:

.. code:: python :name: test_async_class

import asyncio
from async_class import AsyncClass


class MyAsyncClass(AsyncClass):
   async def __ainit__(self):
       future = self.loop.create_future()
       self.loop.call_soon(future.set_result, True)
       await future


async def main():
   instance = await MyAsyncClass()
   print(instance)

asyncio.run(main())

Class AsyncObject

Base class with task store instance and helpers for simple task management.

.. code:: python :name: test_async_object

import asyncio
from async_class import AsyncObject


class MyClass(AsyncObject):
   async def __ainit__(self):
       self.task = self.create_task(asyncio.sleep(3600))


async def main():
   obj = await MyClass()

   assert not obj.task.done()

   await obj.close()

   assert obj.task.done()


asyncio.run(main())

Class TaskStore

TaskStore is a task management helper. One instance has create_task() and create_future() methods and all created entities will be destroyed when TaskStore will be closed via close() method.

Also, a task store might create a linked copy of the self, which will be closed when the parent instance will be closed.

.. code:: python :name: test_tasK_store

import asyncio
from async_class import TaskStore


async def main():
   store = TaskStore(asyncio.get_event_loop())

   task1 = store.create_task(asyncio.sleep(3600))

   child_store = store.get_child()
   task2 = child_store.create_task(asyncio.sleep(3600))

   await store.close()

   assert task1.done() and task2.done()


asyncio.run(main())