在 2012年1月24日星期二UTC+8上午4时50分11秒，Andrea Crotti写道： > On 01/23/2012 06:05 PM, Evan Driscoll wrote: > > > > To play devil's advocate for a moment, if you have the choice between > > two ways of writing something, A and B, where both are basically the > > same in terms of difficulty to write, difficulty to maintain, and > > difficulty to understand, but A is faster than B, even if just by a > > hair, why NOT write A? > > > > It's like 'iter++' vs '++iter' in a C++ for loop. For ints, or for > > some iterators with optimization, it makes no difference. But the > > latter will be faster in debug builds, and *might* be faster in > > release builds if you have a complicated iterator. So why NOT make > > for(...; ...; ++i) the typical way of writing a for loop? > > > > In the Python world, is 'while 1' any harder to understand than 'while > > True'? I'm about as staunch a supporter as you'll find for the idea > > that 'while 1' should throw an exception, and even *I* think that > > 'while 1' is about the least-offensive idiom out there. If 'while 1' > > throws you off, I'd hate to see what you do when you learn that Python > > accepts loops like 'while x' where the condition evaluates to true if > > x is a non-zero integer and false if x is 0. > > > > > > All that said, I like the 'while "stuff to do"' idea. > > > > Evan > > I think it's not the same, iter++ or ++iter is exactly the same in terms > of readability, so of course > if one might be a bit faster, it should be used. > > while 1 works because the 1 is converted to boolean automatically, but > why not just writing a boolean > in the first place? > > It's not bad of course but to me it's not very Pythonic, and reminds me C. > At that point I also prefer the "while 'might be long loop'" idea, which > at least > adds some value *and* it might be very slightly faster too.
A fake generator that can't be cascaded for more processing can be called an iterator by the definition of an iterator. But that is miss-leading in implementing silly trivial non-qualified iterators. -- http://mail.python.org/mailman/listinfo/python-list
