Gennaro Prota wrote:
On Mon, 10 Jul 2006 10:24:29 -0700, "Eric Niebler" <eric@boost-consulting.com> wrote:
[...]
Last week, at Scott's prodding, I took the issue up again and finally resolved the lvalue/rvalue problem. The result is a macro MAX(a,b) that behaves *exactly* like ((a)<(b)?(b):(a)), except that it does not reevaluate its arguments.
Hi Eric,
I thought I could throw an idea even if I had no time to examine your code. Generally speaking I find it grotesque that one has to go through contortions for such simple "primitives" (gcc has had builtin operators for min and max for years now). My question is: is your solution extendible to different operations, such that one could write (not necessarily with that syntax):
f(x, y) = v
rather then
max(x, y) = v
?
In this case you would have a little "framework" to build modifiable lvalues upon binary functions or function objects.
I don't see why not. The techniques used are fairly general. If you have a macro that expands to an expression, and you don't want it to reevaluate its arguments, and you want to preserve const-correctness and lvalue/rvalue-ness, this approach should work. This is probably a lack of imagination on my part, but I can't think of another use besides min/max. What do you have in mind? -- Eric Niebler Boost Consulting www.boost-consulting.com