Show HN: C++ runtime/compile-time detection in constexpr functions

Post by CuriousThinker » Tue, Aug 08, 2017, 3:46 PM UTC

Post by CuriousThinker » Tue, Aug 08, 2017, 3:57 PM UTC

andrepd wrote: post #3

In README: "[...] we can choose to implement a runtime specific algorithm while having a different algorithm for doing something at runtime." Typo?

Post by CuriousThinker » Tue, Aug 08, 2017, 4:31 PM UTC

nickelbox wrote: post #5

CuriousThinker wrote: post #2

I discuss the approach more in depth here: http://saadahmad.ca/detecting-evaluation-context-inside-cons...

So would a valid tl;dr be, "modify the compiled program to catch any invocations not evaluated at compile time and make them return the correct value?"

Post by CuriousThinker » Tue, Aug 08, 2017, 5:29 PM UTC

lbrandy wrote: post #7

Just so I'm clear, what this appears to be doing is the moral equivalent of a function that asks if some constant equals what we know to be its value (true at compile time)? And then at program-init time (via __attribute__((constructor(101)))) changing the value of the constant in the text section so the test is now false? If so, that's both quite clever and something I don't think I want in my codebase :P. The good…

Post by favorited » Tue, Aug 08, 2017, 7:59 PM UTC

petters wrote: post #9

Stuff like this shows that we need to introduce even more things into C++. I am not kidding. There are still many things to improve in C++.