On Feb 23, 11:39 am, Nicola Musatti <[EMAIL PROTECTED]> wrote:
> Paul Rubin wrote:
> > Nicola Musatti <[EMAIL PROTECTED]> writes:
> >>> a = [f(x) + g(y) for x,y in izip(m1, m2) if h(x,y).frob() == 7]
> [...]
> > There you replace one line of code with 40+ lines to get around the
> > absence of GC. Sounds bug-prone among other things.
>
> Come on, you didn't define f, g, izip, h or frob either. It's more like
> 5 to one. Furthermore your code is more compact due to the existence of
> list comprehensions, not because of GC. Had you written a loop the
> difference would be smaller.
So here's three versions, for comparison:
a = [f(x) + g(y) for x,y in izip(m1, m2) if h(x,y).frob() == 7]
a = []
for x, y in izip(m1, m2):
if h(x, y).frob() == 7:
a.append(f(x) + g(y))
std::vector<int> a;
for (std::someiterable<int,int>::iterator i = izip(m1, m2); !
i.finished(); ++i) {
if (h(i->first, i->second).frob() == 7)
a.push_back(f(i->first) + g(i->second));
}
Although the the benefits of static typing can be argued, surely you
can see the clarity tradeoffs that you make for it?
Some notes:
* izip() takes two iterables as input and returns an iterator, using
only O(1) memory at any given time. Your original version got this
wrong.
* I fudged the "!i.finished()" as I couldn't find an appropriate
official version in time for this post
* The iterator can't sanely be copied, so it probably needs to use
refcounting internally. Oops, that's GC...
* Whoever decided to keep C's i++ syntax for iterators should be shot
* x and y aren't named. They could be extracted, but it's just enough
effort that it's probably not worth it in C++.
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