What is the difference between SFINAE and tag dispatching?

What is the difference between SFINAE and tag dispatching?

SFINAE stands for Substitution Failure Is Not An Error, a C++ feature that allows function templates to be selected based on type traits. Tag dispatching, on the other hand, uses types as tags to select function overloads. Both techniques help in template specialization but differ in their approach.

Can you give an example of SFINAE in action?

Sure! Here's a simple example: You can use SFINAE to enable a function only if a type has a specific member function. For instance, you can check if a class has a method foo() and only enable the template if it does.

And how does tag dispatching work?

Tag dispatching works by defining a tag struct and using it as a parameter in your function. Based on the type of the tag passed, you can direct the function to different implementations, allowing for more controlled overload resolution.

Which one is better to use?

It depends on the use case. SFINAE is great for type traits and conditions, while tag dispatching offers clearer control over function selection. Choose based on your specific needs!