std.algorithm and templates

[bearophile via Digitalmars-d-learn]

meat:

> class Woah(){}
> class Bro: Woah{}
> DList!Woah woahs;
>
> and I'm having trouble with..
>
> foreach( bro; woahs.filter!( a => cast(Bro)a !is null))


import std.algorithm, std.container;

class Woah {}
class Bro : Woah {}

void main() {
     DList!Woah woahs;
     foreach (bro; woahs[].filter!(a => cast(Bro)a !is null)) {}
}

Bye,
bearophile