std::function vs. Function Pointers: When Should You Choose What?

Use std::function, Unless There's a Compelling Reason Not To

When working with callback functions in C , the choice between using a C-style function pointer and the newer std::function can be a matter of debate. Let's examine the pros and cons of each option.

C-Style Function Pointers:

• Advantage: No overhead when calling the function.
• Disadvantage: Cannot capture context variables, limiting their use cases.

std::function:

• Advantage: Can capture context variables, making it more versatile.
• Disadvantage: Introduces a small overhead when calling the function.

When to Use std::function:

In most cases, std::function is the preferred choice. It's more flexible and future-proof than function pointers. Unless there are specific performance concerns, it's generally recommended to use std::function for passing around callbacks.

When to Use Function Pointers:

If performance is a critical consideration and the callback function does not need to capture any context variables, then a function pointer may be a better option. However, this scenario is relatively rare.

Third Option: Template Parameter

Consider using a template parameter if you want the callback function to be any callable object. This approach provides flexibility but requires the outer function to be implemented in the header.

Summary Table:

Conclusion:

In general, the advantages of std::function outweigh those of function pointers. It's more flexible, future-proof, and readable. Use function pointers only if there's a specific performance concern or if the callback function does not need to capture any context variables.

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