On 2/28/14 6:36 PM, Mark H. Harris wrote:
On Friday, February 28, 2014 3:03:25 PM UTC-6, Marko Rauhamaa wrote:
Marko
... and between me and you, here is a snip from dmath.py from the atan(x)
function:
if (n**2 < D(1)):
a = __atan__(n)
elif (n == D(1)):
a = gpi/4
elif (n == D(-1)):
a = -(gpi/4)
elif (n < D(-1)):
a = __atan__Lt_neg1__(n)
else:
a = __atan__Gt_1__(n)
This if--elif--else is not only ugly, its just not readable either, and
besides that, its not elegant, nor is it humanly helpful... its does work
though, and its absolutely necessary. ugh.
First, its not immediately clear what it does. Well, there isn't just one
atan(x) routine, there are at least four of them, depending on whether you're
a purist, and they must be selected.
Second, because of the strict intent ideology of python in the first place,
I can't indent this code to make it more readable without breaking python's
syntax.
Third, this is a VERY simple if elif block. More complex ones are much
worse... for human reading that is...
I know its a pain in the neck, but python does need a switch statement.
Is it a stubborn question? I don't really think that almost every modern
computer language has a switch block because of some C paradigm. I think its
because most coders find them useful, at least readable, and therefore
essential.
I don't understand: you show an if/elif chain that cannot be expressed
as a switch statement (because it uses < ), and then conclude that
Python needs a switch statement? That doesn't make any sense.
--
Ned Batchelder, http://nedbatchelder.com
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