On May 24, 7:12 am, Johannes Bauer <[EMAIL PROTECTED]> wrote:
> Carl Banks schrieb:
>
> > p = myfunction()
> > if p:
> > print p
>
> > (I recommend doing it this way in C, too.)
>
> This is okay for if-clauses, but sucks for while-loops:
>
> while (fgets(buf, sizeof(buf), f)) {
> printf("%s\n", buf);
>
> }
In earlier times, the Python idiom was this:
while True:
line = f.readline()
if not line:
break
print line
Not the prettiest thing ever, but it works fine, is readable, and
avoids a temporary variable. In C, given the choice between this or
using assignment expression, I'd say use either one. (But don't use
the version with a temporary, that's ugly as hell.)
More recent versions of Python have obviated the need to use this
idiom by making it possible to iterate over the lines of a file
directly. First they added xreadlines:
for line in xreadlines(f):
print line
Then they deprecated the xreadline function and made it a method:
for line in f.xreadlines():
print line
Then they recommended you no longer use that, and just made file
objects directly iterable:
for line in f:
print line
The point is, the Python language developers do share your concern
about these things. However, they still think assignment epxressions
are a very bad idea, so they've sought other solutions to these
issues.
(But, as I said, they have yet to provide an alternative for elif
clauses; you're stuck with workarounds there.)
Carl Banks
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