Templated delegate as template argument for structs

[Simon van Bernem]

I have the following struct declaration:


struct Hash_Table(Key, Value, u32 delegate(ref Key) 
custom_hash_function = null){

...

}


When I try to instance the Type like this:


Hash_Table!(Component*, Component_Tick_Info, (c) => 
hash32(c.handle.bitfield)) my_hash_table;


I get the following compile error


source\vbl.d(2338): Error: undefined identifier `Key`
source\vessel.d(840):        while looking for match for 
`__lambda4!Key`
source\vessel.d(840):        while looking for match for 
`Hash_Table!(Component*, Component_Tick_Info, (c) => 
hash32(c.handle.bitfield))`


vbl.d(2338) is the line of the struct declaration.

I take it from the error that the problem is not actually the 
delegate that I am passing, but the fact that the delegate type 
has another template parameter as the argument type. Can template 
arguments in D not reference previous template arguments? Is 
there some way I can get around this?