On Fri, 17 Apr 2009 18:24:04 +0400, Steven Schveighoffer <schvei...@yahoo.com>
wrote:
> On Fri, 17 Apr 2009 09:44:09 -0400, Leandro Lucarella <llu...@gmail.com>
> wrote:
>
>> I don't fully understand the example though. In writefln((v.qq = 5).i),
>> how is that B.i is assigned to 5 if the opDotExp("qq", 5) don't
>> propagate
>> the 5 to the new B()?
>
> I think it translates to
>
> opDotExp("qq") = 5
>
> Without knowing the signature of qq, how is the compiler supposed to
> infer that it is a property? In fact, I think this might be a
> limitation of this syntax, you can't define dynamic properties.
>
> I for one, can't really see a huge benefit, but then again, I don't
> normally work with dynamic-type langauges. It looks to me like a huge
> hole that the compiler will ignore bugs that would have been caught if
> the methods were strongly typed:
>
> class c
> {
> void opDotExp(char[] methodname,...)
> {
> if(methodname == "mymethod")
> callMyMethod();
> else
> throw new Exception("bad method name: " ~ methodname);
> }
> }
>
> void foo(c myc, bool rarelySetToTrue)
> {
> if(rarelySetToTrue)
> myc.mymethud(); // compiles, will throw runtime exception
> }
>
> Also, how do you overload the return value? Using this proposal, you
> can't have different dynamic methods that return different types.
>
> -Steve
Here is how it could be done:
class C
{
auto opDot(string methodName, T... args)(T args) // opDotExp renamed to
opDot
{
static if (methodName == "length") {
return _length; // return type is size_t
} else static if (methodName == "resize") {
_resize(args); // return type is void
}
}
}
This is a great use-case for compile-time "static switch". Can we haz one,
please?
