• David Medlock (22/23) Dec 09 2004 template TVector(T,uint SZ)
• Ben Hinkle (29/52) Dec 09 2004 The return type of MyFunct is Vector but it is assigning to a variable o...

David Medlock <amedlock nospam.org> writes:

template TVector(T,uint SZ)
{
   class Vector
   {
     T[SZ]     values;

     Vector  MyFunct(T f)
     {
       return new Vector();
     }
   }
}

class V3f : TVector!(float,3).Vector {}

void main( char[][] arg )
{
   V3f  v = new V3f();
   v = v.MyFunct(100.0f);
}

...
compiler gives me:

 "C:\dmd\bin\dmd.exe" -debug -c E:\proj\temp\bug2.d

E:\proj\temp\bug2.d(23): cannot implicitly convert expression 
cast(Vector )(v).MyFunct(100) of type Vector to V3f

Should not this conversion be implicit?

"Ben Hinkle" <bhinkle mathworks.com> writes:

"David Medlock" <amedlock nospam.org> wrote in message
news:cp9ng4$c9p$1 digitaldaemon.com...
 template TVector(T,uint SZ)
 {
    class Vector
    {
      T[SZ]     values;

      Vector  MyFunct(T f)
      {
        return new Vector();
      }
    }
 }

 class V3f : TVector!(float,3).Vector {}

 void main( char[][] arg )
 {
    V3f  v = new V3f();
    v = v.MyFunct(100.0f);
 }

 ...
 compiler gives me:

  > "C:\dmd\bin\dmd.exe" -debug -c E:\proj\temp\bug2.d
 E:\proj\temp\bug2.d(23): cannot implicitly convert expression
 cast(Vector )(v).MyFunct(100) of type Vector to V3f

 Should not this conversion be implicit?

The return type of MyFunct is Vector but it is assigning to a variable of
type V3f, which is not allowed without a cast. It is like
class Foo;
class Bar : Foo;
...
Bar x;
...
x = new Foo;
...
But this is allowed:
Foo y;
y = new Bar;

By the way, your example can be shortened to:
class Vector(T,uint SZ)
{
  T[SZ]     values;

  Vector  MyFunct(T f)
  {
    return new Vector();
  }
}

class V3f : Vector!(float,3) {}

void main( char[][] arg )
{
   V3f  v = new V3f();
   v = v.MyFunct(100.0f);
}