How to get the type of a variable?

[rempas]

How can I use a compile time if (#if) to mach the type of a variable? In D, I would had the following code:

void print_type(T)(T arg) {
  static if (is(typeof(arg) == string))
    write("It is a string");
  else static if (is(typeof(arg) == int))
    write("Is is an int");
}

Of course I know that other stuff are different in Vox but what I'm interested is the conditional code for the if and else if statement

[MrSmith33]

I didn't implement typeof yet, but in that concrete example you could use T

[rempas]

Thanks! Do you plan to change this behavior some time in the future so we can compare them? Also why have you choose to make string literals get passed as slices rather than simple pointers who are faster? Is there a particular advantage?

[MrSmith33]

Yea, I'm thinking about type deduplication, but it isn't an easy thing to implement. So may take a while.

String literals are zero terminated, and they implicitly cast to u8* (useful for C interop). Also, you can get the raw pointer with .ptr property if you really want that. Otherwise strings are just regular slices and knowing the length is always a good idea.

[rempas]

Yea, I'm thinking about type deduplication, but it isn't an easy thing to implement. So may take a while

That sounds awesome! Of course it will take a lot of time to implement that but who cares really? Good things take time so it makes sense!

Now about strings. Are slices Objects or special types that are handled by the compiler. My point being, when the implicit conversion happens, will this be just as taking the .ptr part of the slice or will we need to have instructions to make a conversion at compile time? Or is it a compile time things that you only play with the memory that is used? I'm so confused...

[MrSmith33]

Slices are special types, but they are effectively a struct with 2 members ulong length; T* ptr. So string literal is a struct literal with length and pointer to static data. The implicit conversion of string to char* is the same as using .ptr on the literal. See spec/index.md#slices

[rempas]

Cool! That's nice! Thanks a lot for you time man!