Identifier (...) is too long by X characters

[Sean Kelly]

Tom S wrote:
> Don Clugston wrote:
>> If Tuple!() works with a nesting level of 50, the limit would have to 
>> be pretty big.
> 
> Yeah, and it would cause DMD to eat RAMs like a medium-sized dragon.
> 
> 
>> Maybe in the future, we'll be able to add some kind of 'final' 
>> declaration to templates, which would indicate that they don't need to 
>> be stored in the object file or library, and can be discarded from the 
>> symbol table as soon as they are instantiated. This would be 
>> particularly useful for recursive templates, which can easily spew 
>> reams of garbage into the object file.
> 
> My thoughts exactly :) Right now I'd be happy with anything that worked 
> though...
> 
> 
> And while we're at recursive templates, don't you think that the 
> limitation for recursive templates, which causes the error 'template 
> instance recursive template expansion for template argument X' is pretty 
> arbitary ? It can be hacked around, after all:
> 
> 
> // tmp.d
> import std.stdio;
> 
> 
> struct Foo(T/*, int dummy=0*/) {
>     Foo!(Foo!(T/*, dummy+1*/)) rec()() {    // line 5
>         Foo!(Foo!(T/*, dummy+1*/)) res;
>         return res;
>     }
> }
> 
> 
> void main() {
>     Foo!(int) a;
>     writefln(typeid(typeof(a)));
>     auto b = a.rec!()();
>     writefln(typeid(typeof(b)));
> }
> // ----
> 
> tmp.d(5): template instance recursive template expansion for template 
> argument Foo
> 
> But when you uncomment the 'dummies', it compiles and runs without any 
> problems...
> 
> Yeah, I know, the error is an artifact of how the instantiation works, 
> that it's not 'lazy' like in C++. But since it can be fooled into 
> working, couldn't DMD apply the hack automagically ?

I don't know.  To do so would be like allowing:

struct S
{
     S val;
}

I'm not sure I'd want the compiler to try and "fix" a mistake I'd made 
involving this.  Adding an integer is pretty easy anyway.


Sean