On Wed, 29 Jul 2009 10:16:33 -0400, grauzone <n...@example.net> wrote:

Daniel Keep wrote:
Maybe the compiler could rewrite the above as:
 auto t = a.b;
t.c = 3;
a.b = t;
 Unless it can prove it doesn't need to.  Same solution as to the op=
conundrum.

Yes! At least that's what the user wants.

The compiler has to detect, that the object was modified at all. (To know whether it should generate code to write back the property.) Would this make the compiler much complexer?

You also have to deal with nested properties:

a.b.c.d = 3;

turns to

auto t = a.b;
auto t2 = t.c;
c.d = 3;
t.c = t2;
a.b = t;

???

Yeah, I think this idea is no good. a.b.c.d.e.f = 3, results in one gigantic mess, which the user might not want.

Properties don't have to be exactly like fields. I think we need to get away from that idea.

It would be nice if the compiler could help by simply rejecting what it can reject (assignment to rvalues), but other than that, there's not much that can be done.

This can be detected in simple cases, but in the case where the end point is a function, it will be difficult or impossible.

I don't believe the problem needs to be solved.

-Steve

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