On Monday, 25 May 2015 at 07:33:49 UTC, ketmar wrote:
On Sun, 24 May 2015 19:30:52 +0000, kinke wrote:
So for the 2nd assignment's left-hand-side, the index is
evaluated
before evaluating the container! Please don't tell me that's
by design.
:>
it is. at least this is what i was told when i faced the
similar issue.
"WONTIFX, STFU".
To be fair, the example that the OP gave is almost the same thing
as
foo(++i, ++i);
whereas what you came up with had a lot more layers to it, with
whole chains of function calls affecting each other. With the
kind of example you came up with, even with defining the
evaluation as strictly left-to-right, you would _still_ run into
screwy problems with stuff easily being mutated in a different
order than you expected.
Defining the order of evaluation as being strictly left-to-right
will avoid some of the common bugs cause by folks foolishly doing
something like
foo(++i, ++i);
but the reality of the matter is, if you start doing stuff like
mutating the arguments inside of the function inside of the
function when the same arguments are being passed to other
functions in the same expression, you _will_ have weird and
unexpected stuff happening. It might be completely well-defined
and consistent, but it may not be what you expect, and even if it
is, a slight change to the code could change the order. So, the
kind of stuff that you're complaining about not being able to do
really shouldn't be done regardless of how well-defined the order
of evaluation is. It's just begging for trouble.
- Jonathan M Davis
