[Octave-bug-tracker] [bug #51962] "A++" assigns to 'ans' while "A += 1" and "A = A + 1" do not

[Mike Miller]

Follow-up Comment #10, bug #51962 (project octave):

That's what I was suggesting in comment #2, if there is a way to determine
that the "A++" expression would not be assigned to some other value and
suppress the extra copy of A made. I'm not sure that's possible, but worth
looking into.

It occurred to me that it's also worth documenting that "++A" is more
efficient than "A++". The prefix operator does not need to create an extra
copy of A. In C++ terms this is often mentioned to avoid making unnecessary
expensive copies of objects. In Octave this should be mentioned because it
avoids making expensive copies of large arrays due to Octave's COW behavior.


>> A = rand (1e4);  ## Octave allocates 800 MB
>> ++A;  ## A incremented, ans == A, no extra memory used
>> A++;  ## A incremented, ans != A, 1600 MB now used


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