Скачать или смотреть Triggering a Timer in Python: Start a Thread Timer Directly

Learn how to trigger a function immediately after initializing a timer in Python using the RepeatedTimer class. Discover the right implementation and tips to manage your thread timers effectively.
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This video is based on the question https://stackoverflow.com/q/67822932/ asked by the user 'Louis Brahmi' ( https://stackoverflow.com/u/10148787/ ) and on the answer https://stackoverflow.com/a/67837330/ provided by the user 'Sven Eberth' ( https://stackoverflow.com/u/3749896/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Triggering a Timer in Python: Start a Thread Timer Directly

When working with timers in Python, you might encounter situations where you want a function to execute immediately upon timer initialization as well as at regular intervals. This can often create confusion, especially when trying to utilize custom thread timers. In this guide, we’ll explore an interesting challenge: how to call a function directly after starting a RepeatedTimer and ensure that it's also executed periodically. Let’s dive into the solution!

The Problem

In your code, you have a custom timer class called RepeatedTimer. When initializing the timer, you want to trigger the __runSequence() function right away. However, using the following line causes errors:

[[See Video to Reveal this Text or Code Snippet]]

The problem arises from passing the result of self.__runSequence(sequence) instead of the function itself, resulting in an error indicating that the function does not receive the required argument.

The Solution

The key to solving this issue lies in modifying the initialization process of the RepeatedTimer class. You need to ensure that your function gets executed immediately and then continues to run at specified intervals. Here's how you can implement it:

Step 1: Modify the RepeatedTimer Class

Update the _init_ method of the RepeatedTimer class to call _run() directly instead of start(). This change allows the function to execute immediately upon initialization.

Here’s the revised code for the RepeatedTimer class:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Test the Implementation

After modifying the RepeatedTimer, you can initialize your timer and see it working in action. Here’s an example of using the modified class:

[[See Video to Reveal this Text or Code Snippet]]

Expected Output

When you run the modified code above, the output should look something like this:

[[See Video to Reveal this Text or Code Snippet]]

Notice that the first call to the function occurs before the "After initialization" message, confirming that it executed immediately upon the creation of the timer.

Conclusion

By properly structuring your RepeatedTimer class to include immediate execution upon initialization, you can streamline your coding process when working with timer functions in Python. Just remember to pass the function itself, not the result, during initialization! With these tips, you'll be managing thread timers more effectively in your Python applications.

Whether you're building a simple timer or a complex application requiring periodic function execution, the adjustments made here will help you implement your timers seamlessly. Happy coding!