On Thu, 22 Dec 2005 01:41:34 +1100 in comp.lang.python, Steven
D'Aprano <[EMAIL PROTECTED]> wrote:
[...]
>Well, let's find out, shall we?
[...]
>A small but consistent speed advantage to the try...except block.
>
>Having said all that, the speed difference are absolutely trivial, less
>than 0.1 microseconds per digit. Choosing one form or the other purely on
>the basis of speed is premature optimization.
Or maybe on which actually works. LBYL will fail to recognize
negative numbers, e.g.
def LBYL(s):
if s.isdigit():
return int(s)
else:
return 0
def JDI(s):
try:
return int(s)
except:
return 0
test = '15'
print LBYL(test), JDI(test) #-> 15 15
test = '-15'
print LBYL(test), JDI(test) #-> 0 -15
>
>But the real advantage of the try...except form is that it generalises to
>more complex kinds of data where there is no fast C code to check whether
re: Generalization, apropos a different thread regarding the %
operator on strings. In Python, I avoid using the specific type
format conversions (such as %d) in favor of the generic string
conversion (%s) unless I need specific field width and/or padding or
other formatting, e.g.
for p in range(32):
v = 1<<p
print "%2u %#010x : %-d" % (p,v,v)
Regards,
-=Dave
--
Change is inevitable, progress is not.
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