Question

If I have a class such as the following:

import std.traits;

class Test(T) if(isCallable!T)
{
 alias ParameterTypeTuple!T Parameters;
 alias ReturnType!T delegate(Parameters) DelegateType;

 DelegateType m_delegate;

 void Foo(void ** arguments)
 {
  // I want to convert the void* array to
  // the respective type of each argument
  m_delegate(arguments);
 }
}

How can I convert a C array of void pointers to their respective type (where their type is defined in Parameters and the length ofarguments equals the length of Parameters) and then call the function?

I tried to do this using a tuple like the following:

void Foo(void ** arguments)
{
 Tuple!(Parameters) tuple;

 foreach(index; 0 .. Parameters.length)
 {
  // Copy each value to the tuple
  tuple[index] = *(cast(Parameters[index]*) arguments[index]);
 }

 // Call the function using the tuple (since it expands to an argument list)
 m_delegate(tuple);
}

But this does not compile because the compiler complains about “variable index cannot be read at compile time”. Any ideas?

Answer 1

Do something along these lines:

ParameterTypeTuple!T args;

foreach(i, arg; args) {
    args[i] = cast(typeof(arg)) arguments[i];
}

and you should be started