Re: C like op= proposal

[Andi Kleen <ak-uu@muc.de>]

Samuel Tardieu <sam@ada.eu.org> writes:

> >>>>> "Gautier" == Gautier  <Gautier.deMontmollin@Maths.UniNe.CH> writes:
> 
> Gautier>   a(b(c,d+e(f,g)).h(i,j)) := a(b(c,d+e(f,g)).h(i,j)) + 1;
> 
> Gautier> which can be horribily long and unlikely to be catched by the
> Gautier> optimizer -> 2x too slow (at least: the extra code makes a
> Gautier> penalty for processor cache).
> 
> Where did you get the impression that the optimizer would miss this?

[..] discussion about +=,++ and friends for better code snipped.

I would like to have += in Ada (perhaps not ++,--) simply because it 
is more expressive. My brain wraps easier to "increase X by Y" than
to "set X to the sum of X and Y"[1] Ada is about making it easy for the
reader, isn't it? +=, -= make it clear that there is a side effect
that takes the old value into account, with the spelled out way
"x := x + 1" I have to determine that first. With simple "x" it is easy,
but e.g. with Gautier's example above it requires real mental work that 
distracts me from my primary job.  Not that this is impossible,
it is just that the first way is IMHO better readable because it makes
the intent of the author more clear.


-Andi

[1] To attribute correctly this is an old argument from, I believe
Dennis Ritchie, in a prehistoric article about C. I think he's right.

-- 
This is like TV. I don't like TV.