Self-referencing template parameters

[Erik Rasmussen]

Erik Rasmussen wrote:
> Oskar Linde wrote:
> 
>> The problem is that this line contains a recursive instantiation:
>> abstract class Animal(T : Animal!(T))
>>
>> Animal!(T) has to be instantiated before the compiler knows how to 
>> what type it is.
>>
>> But if you place a static assert in a place outside what the compiler 
>> needs to deduce the type:
>>
>> class Animal(T) {
>>     this() {
>>         static assert(is(T : Animal));
>>     }
>>     public abstract T[] procreate(T mate);
>> }
>>
>> Things work as they should.
>>
>>
>> /Oskar
> 
> 
> Thanks, but...
> 
> test.d
> ---
> abstract class Animal(T)
> {
>   this()
>   {
>     static assert(is(T : Animal));
>   }
> 
>   public abstract T[] procreate(T mate);
> }
> 
> class Monkey : Animal!(Monkey)
> {
>   public Monkey[] procreate(Monkey mate)
>   {
>     return new Monkey[2];
>   }
> }
> 
> int main(char[][] args)
> {
>   new Monkey();
> }
> ---
> 
> When I compile, I get:
> test.d: variable test.Animal!(Monkey).Animal.this.this abstract cannot 
> be applied to variable
> test.d:3: variable test.Animal!(Monkey).Animal.this.__result abstract 
> cannot be applied to variable
> 
> Now what?  Line 3 is the "this()" line.
> 
> Erik

Oops.  The problem was the "abstract" on the very first line.  Bad Java 
habit.

Erik