Feature request: function prototypes

[Ary Borenszweig]

Christopher Wright wrote:
> Robert Fraser wrote:
>> This may seem like a pretty stupid request, but since I use a lot of 
>> version() statements in my code; it'd be really cool to have something 
>> like function signatures at the top of my file. When I declare my 
>> versioned functions, I'd love to be able to have them checked against 
>> prototypes declared above their use, as a first line of defense (so I 
>> don't need to r-test it on different OSes and libraries if I make an 
>> obvious change to one of the signatures or something).
> 
> Have a unittest? To satisfy your purposes, it just needs to call each 
> function, even with invalid input. Then if everything compiles with 
> -unittest, you're golden, even if that crashes.
> 
> Satisfies your requirements, anyway, and in any situation, you'd be 
> duplicating the signature three times.

But unittests are run with specific version flags.

I think he means something like this:

---
prototype {
   int someFunc(float, bool);
}

version(one) {
   int someFunc(float f, bool b) {
     // ...
   }
} else {
   int someFunc(float f, bool b) {
     // ...
   }
}
---

Now, if you change the signature of someFunc inside of version(one) 
you'll get a compiler error, because the prototype "int someFunc(float, 
bool)" would not be found if version is "one". Alternatively, if you 
change the prototype inside the "prototype { }", you'll get two compiler 
errors: in "one" the prototype doesn't exist, neither in the "else". 
That way you can maintain synchronized the two version blocks.

The problem is, how to implement this? The compiler would need to check 
all possible combinations of versions, debugs, static ifs, etc.

By the way, this will also allow tools to provide good refactoring support.