Resolved: Enabling C++ constructor subject to say std::is_floating_point

In this post, we will see how to resolve Enabling C++ constructor subject to say std::is_floating_point<T>

Question:

I’m trying to enable a default constructor only if the class’s template parameter is floating point. Note T is not a parameter type nor return type but the class template type.
I tried putting the following in front of the constructor
And I tried putting the std::enable_if_t...= true stuff as an argument to the default constructor (and various other attempts).
Both of these tries rightfully complains about it1 so that’s good, but when I remove that, they both also complain about it2! I don’t understand and can’t find the magic incantation.
Thanks for any insights.
I forgot to mention, I’m stuck on C++17.

Best Answer:

Use requires:
Or, in C++17:
The SFINAE condition must depend on a template parameter of the function itself. Otherwise it can be checked when the class is first instantiated, even if the function isn’t used.
I also tweaked a few things, purely for style.

If you have better answer, please add a comment about this, thank you!

Source: Stackoverflow.com