How do I the temlate parameter name as string?

[PacMan via Digitalmars-d-learn]

ParameterIdentifierTuple from std.traits did work fine for 
regular functions but not for template functions:

Error: template instance 
`std.traits.ParameterIdentifierTuple!(f)` does not match 
template declaration `ParameterIdentifierTuple(func...) if 
(func.length == 1 && isCallable!func)` (foo)

f is defined as:

void f(T)(T t, string p)
if(is(T == A) || is(T == B))
{
        // ...
}

my goal is get "p" as string.