Hi,
Please excuse the cross-post with D.learn. People have been helpful
there with workarounds, but I'm bringing it here in the hope that we can
discuss a language enhancement.
So - could support for 'ref' local variables be added, or is there a
reason not to? I want to write something like:
MapTile[] map; // It's a struct
ref MapTile tile=map[y*w+x];
tile.id=something;
tile.isWall=true;
someFunctionThatTakesRefMapTile(tile);
Here are the alternatives I'm aware of:
- Pointers. I'm using these for now, but it means extra & and *
operators sometimes, it makes 'ref' less tempting where it IS allowed
since it's not consistent, and I got the impression that pointers are
only encouraged when interfacing with C code, so I was surprised to find
I needed them here. (Am I wrong about this last part?)
- 'with' - doesn't work because of the function call, and also because
it would only support one tile at once, whereas I sometimes have a few.
For example I might define 'below=map[(y+1)*w+x]' at the same time, and
then I can write "if (below.id==CLEAR) {below=tile; tile.id=CLEAR;}".
- Class instead of struct - I don't want to do this since the array is
quite big and the struct pretty small, and that would be a lot of extra
overhead.
- Some kind of solution involving 'pretend to be a reference' types with
difficult-to-read implmenetations and optimisation caveats, not worth
the fuss compared to using pointers.
Incidentally, this code is already supported:
int x,y; getValues(x,y);
void getValues(ref int x, ref int y) ...
Yet it's not clear that x and y are passed by reference - whereas the
currently unsupported case with local variables doesn't suffer from that
readability issue, and indeed "below=tile" is much more readable than
"map[(y+1)*w+x]=map[y*w+x]".
I'd also expect it's trivial in terms of code generation, as parameters
and local variables are very similar.
So it strikes me as a no-brainer :)
Thanks,
Ben :)
