24.01.2012 8:43, Andrej Mitrovic пишет:
But I did implement them poorly, this is better:
import std.traits;
template KeyType(AA)
if (isAssociativeArray!AA)
{
static if (is(AA V : V[K], K))
{
alias K KeyType;
}
}
template ValueType(AA)
if (isAssociativeArray!AA)
{
static if (is(AA V : V[U], U))
{
alias V ValueType;
}
}
Might I suggest that it be implemented this way:
template KeyType(AA)
{
static if (is(AA V : V[K], K))
{
alias K KeyType;
}
else static assert( 0, "Not associative array: " ~ AA.stringof );
}
Of course, most likely that user already did type check, but if not,
this will give less cryptic error:
Error: static assert "Not associative array: int"
instantiated from here: KeyType!(int)
, instead of:
Error: template instance KeyType!(int) KeyType!(int) does not match
template declaration KeyType(AA) if (isAssociativeArray!(AA))
