Adding delay function

[VahilaK]

Add a function which facilitates to run a task after some time in background.

This PR fixes #1415

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[codecov]

Codecov Report

Merging #1431 (bd55e0e) into master (01df836) will decrease coverage by 0.09%.
The diff coverage is 40.00%.

Impacted Files	Coverage Δ
src/core/toga/app.py	84.80% <40.00%> (-1.13%)	⬇️

[freakboy3742]

Thanks for the PR; while this does implement functionality that will run on a delay, it's not exactly what #1415 was requesting.

The original request was to install a background task, and that task included a 5 second delay.

This PR implements an asynchronous method that does a sleep as it's first step.

The reason this matters is that you can only invoke your version of the method from an asynchronous context. This means it can't be invoked from a standard button handler, or from a generator.

[VahilaK]

@freakboy3742 I apologize for the delay in reverting. I understand there would be an issue with asynchronous context but I am not really sure on how to take this forward. One idea I have is to create a new thread which would add the method to background after the thread sleeps for the timeout duration. I am planning to use time.sleep in the new thread, this way there wouldn't be any asynchronous functions. Please let me know your views on this approach.

[freakboy3742]

@freakboy3742 I apologize for the delay in reverting. I understand there would be an issue with asynchronous context but I am not really sure on how to take this forward. One idea I have is to create a new thread which would add the method to background after the thread sleeps for the timeout duration. I am planning to use time.sleep in the new thread, this way there wouldn't be any asynchronous functions. Please let me know your views on this approach.

There's no need to use threads - this can be done entirely with asyncio. However, you need to pay close attention to what it is that you're putting on the background task list.

Your implementation here is "sleep for 2 seconds and then call a function". What we need is "call a function right now whose first action is to sleep for 2 seconds".

[freakboy3742]

Closing due to lack of activity.