Mike Meyer wrote: > Riccardo Galli <[EMAIL PROTECTED]> writes: > > >>On Fri, 24 Jun 2005 09:00:04 -0500, D H wrote: >> >> >>>>Bo Peng wrote: >>>> >>>> >>>>>I need to pass a bunch of parameters conditionally. In C/C++, I can >>>>>do func(cond1?a:b,cond2?c:d,.....) >>>>> >>>>>Is there an easier way to do this in Python? >>>> >>>> >>>The answer is simply no, just use an if statement instead. >> >>That's not true. >>One used form is this: >>result = cond and value1 or value2 >> >>which is equal to >>if cond: >> result=value1 >>else: >> result=value2 >> >> >>another form is: >> >>result = [value2,value1][cond] >> >> >>the first form is nice but value1 must _always_ have a true value (so not >>None,0,'' and so on), but often you can handle this. > > > Note that [value2, value1][cond] doesn't do exactly what cond ? value1 : > value2 > does either. The array subscript will always evaluate both value2 and > value1. The ?: form will always evaluate only one of them. So for > something like: > > [compute_1000_digits_of_pi(), compute_1000_digits_of_e][cond] > > you'd really rather have: > > cond ? compute_1000_digits_of_e() : compute_1000_digits_of_pi() > > There are other such hacks, with other gotchas. > > <mike
If you use function like you suggest, then this will work. result = [compute_1000_digits_of_pi, compute_1000_digits_of_e][cond]() Note the trailing ()'s which will call one or the other function after the condition is evaluated but not both. Regards, Ron -- http://mail.python.org/mailman/listinfo/python-list
