On Wednesday, 10 June 2015 at 17:43:36 UTC, Ali Çehreli wrote:
On the other hand, if it's a manifest constant (enum, const static, etc.) then by definition it cannot be mutated. If we allowed mutation of compile-time expressions, then we would have a complicated language.
Unfortunately, the halting problem says that the analyzer does not exist. Although I don't believe it!
enum i = 42; enum j = foo(i); // Did foo() use 42 or 43? i = 43; enum k = foo(i); // Did foo() use 42 or 43? How can an enum value be changed? I find the above confusing.
So in fact, if `int` is evaluated at compile time, then we won't need constants or enums. Because they almost would not make sense. Although the issues associated with immutability, complex, I think they can be solved differently.
The great thing about D's CTFE is that we can use arbitrarily complex expressions as long as they are available at compile time. For example, it is possible to make 'i' above a foreach loop variable and call foo() with different values.
There is nothing great. Everything is based on constexpr of C++. I want something more revolutionary :)
What is your use case? I feel like it can be solved by other means.
There is no precedent special :) I just want to know more about the possibilities of D and the possibility of its compiler. D made me a terrible interest in compilers :)
