Don wrote:
Andrei Alexandrescu wrote:
Don wrote:
Christopher Wright wrote:
Don wrote:
The creation of temporaries during expressions is something I'm
currently working on solving. The case you mentioned is addressed
by a proposal I made long ago:
The easiest way is to add an intermediate struct. This takes a fair
bit of manual effort, though, and prevents you from using auto.
That particular case is the easiest possible one. The case x = y - x,
for example, is much more difficult to recognize.
Essentially, you need a struct MyClassAddition that just records
operands. Then give it an implicit cast to MyClass that does the
work. This is an ugly solution because you need to duplicate the
operator overloads on MyClassXXX as well as MyClass.
I believe I got this solution from an article by Andrei. It should
work pretty well for classes that define few overloads.
I'm talking about a language solution. I want to solve this for the
general case.
Don't forget that the case you are solving is not general enough
because you are focusing on eliminating temporaries, which is only
part of the story. I suggest you make place in your thoughts for loop
fusion.
Yes. That's the classic problem for matrices, but I'm still trying to
work out if it is really a general problem. I was hoping to see some new
use cases, but none so far.
I think the matrices case is important enough to make it its own class
of problems. For example, bitmap processing is another instance of
matrix usefulness, just one that doesn't usually jump to mind when
thinking of matrices.
Then how about BigInt and arbitrary precision numbers? Wouldn't fusing
some operations together be useful?
Andrei
