Скачать или смотреть How to Easily Add a Timer Reset Routine to Every Function in an Array of Function Pointers in C+ +

Discover how to integrate a `timer reset` feature into your C+ + callback functions without altering their signatures. Learn to use templates for dynamic wrapper functions!
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This video is based on the question https://stackoverflow.com/q/64502926/ asked by the user 'Micha' ( https://stackoverflow.com/u/11076189/ ) and on the answer https://stackoverflow.com/a/64504066/ provided by the user 'JaMiT' ( https://stackoverflow.com/u/9837301/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Adding a Timer Reset Routine to Function Pointers in C+ +

When developing applications in C+ + , especially in embedded systems, you often encounter challenges while working with function pointers and callbacks. One common question from developers is how to add a standard routine—like resetting a timer—to an array of function pointers without altering their original signatures. This guide will guide you through the solution, providing clear explanations and examples to help you achieve this seamlessly.

The Challenge

You have a well-defined callback signature:

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

With a corresponding array holding pointers to these callbacks:

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

You can add callbacks to this list through a function like:

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

However, when these callbacks are invoked upon certain events, you want to perform additional tasks—namely, resetting a timer:

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

The challenge lies in adding this routine without modifying the signatures of your existing callbacks or stepping away from function pointers, as these are required for interaction with an external library.

The Simple but Inefficient Solution

Initially, one might think of simply editing each callback function to include myTimer.reset(); at the start. However, this approach is not ideal since:

Not every call to a callback may require resetting the timer.

It can lead to future maintenance issues, especially if you need to change functionality later.

A Better Approach: Wrapper Functions

Instead of modifying each callback individually, a more elegant solution would be to create a wrapper function:

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

This allows you to reset the timer every time wrap1 is invoked, while still allowing other calls to use fun1 directly.

However, writing a separate wrapper function for each callback is tedious and not scalable.

The Template Solution

To avoid redundancy and keep your code clean, you can leverage C+ + templates. By creating a generic wrapper function with templates, the compiler can generate specialized wrappers as needed, allowing you to keep your code DRY (Don't Repeat Yourself). Here’s how:

Define a template function that takes the function pointer as a template parameter:

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

Add your callbacks using this template function:

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

Why This Works

Flexibility: You avoid writing multiple wrapper functions for each callback.

Type Safety: The template ensures that the function pointers you are passing conform to the defined callback type.

Maintainability: If you need to change the behavior later, you only need to modify the template wrapper function.

Conclusion

By employing templates, you can elegantly add standard routines like a timer reset to your C+ + callbacks without the complications of altering their signatures or creating excessive boilerplate code. This not only enhances the maintainability of your code but also adheres to the best practices of software development.

Next Steps

Feel free to explore further if you have complex callback types or require additional routines! If you're facing additional challenges or need improvements tailored to your specific scenario, don’t hesitate to ask additional questions.



Implementing a timer reset for every function pointer does not have to be cumbersome. With this template-based approach, you can strike a perfect balance between functionality and simplicity in your embedded C+ + projects.