Workaround for DIP 1005

[Chris Wright via Digitalmars-d]

On Tue, 07 Feb 2017 15:00:17 +0000, Andrea Fontana wrote:
> I don't understand why we can't use a template like:

You can. However, that makes things awkward when you want to pass that as 
a delegate. It makes it awkward to read. You don't get to specify the 
return type unless it happens to be the same as a parameter type.

A near equivalent is:

  template extractDate()
  {
    import std.datetime;
    Date extractDate(SysTime time)
    {
      return time.date;
    }
  }

Better type checking, but you need to refer to it as `extractDate!()` 
sometimes. That's still better than having to refer to it as `extractDate!
(SysTime)`.