Re: Order of argument evaluation in C++, etc.

graham.matthews@pell.anu.edu.au writes:
>> Time to add a note of "futureness" to the debate. All this argument
>> about order of evaluation, the disadvantages, advantage etc is all
>> very uniprocessor based.


chase@centerline.com (David Chase) writes:
>There's a few problems with your reasoning, as I see it.
>First of all, I think it will be very hard for C++ programmers
>to move to parallel execution.


Apologies if I missed the boat but I was not commenting on C++
directly, rather in the ideas of side effect expressions etc.
My comments do apply to C++ though (see below).


>Second, (once again) where's your measurements? How much potential
>parallelism are we giving up here, relative to what we've got or
>will get? How much current unreliability should we trade off
>against some mythical future parallel performance?


You are potentially giving up a huge amount of parallelism. Take the
call,


x = f(g(...), h(...))


Since functions are expressions and can have side effects g() and h()
cannot be executed in parallel (unless you can statically determine
which source code g and h refer to and analyse that. If you want to
make life harder do something similar to the above with virtual
methods.


graham
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