Steven D'Aprano wrote:
On Wed, 09 Dec 2009 18:50:29 +0000, Nobody wrote:
On Tue, 08 Dec 2009 21:02:44 -0800, Kee Nethery wrote:
I string together a bunch of elif statements to simulate a switch
if foo == True:
blah
elif bar == True:
blah blah
elif bar == False:
blarg
elif ....
This isn't what would normally be considered a switch (i.e. what C
considers a switch).
Anyone would think that C was the only programming language in
existence...
A switch tests the value of an expression against a
set of constants.
In C. Things may be different in other languages.
For example, I recall the so-called "4GL" (remember when that was the
marketing term of choice for interpreted programming languages?)
Hyperscript from Informix. I can't check the exact syntax right now, but
it had a switch statement which allowed you to do either C-like tests
against a single expression, or if-like multiple independent tests.
Moving away from obsolete languages, we have Ruby which does much the
same thing: if you provide a test value, the case expression does a C-
like test against that expression, and if you don't, it does if-like
multiple tests.
http://www.skorks.com/2009/08/how-a-ruby-case-statement-works-and-what-
you-can-do-with-it/
If you were writing the above in C, you would need to
use a chain of if/else statements; you couldn't use a switch.
Compiled languages' switch statements typically require constant labels
as this enables various optimisations.
Pascal, for example, can test against either single values, enumerated
values, or a range of values:
case n of
0:
writeln('zero');
1, 2:
writeln('one or two');
3...10:
writeln('something between three and ten');
else writeln('something different');
end;
Originally the 'case' statement in Pascal didn't support ranges or a
default; they started as non-standard extensions in some
implementations. Originally, if none of the values matched then that
was a runtime error.
--
http://mail.python.org/mailman/listinfo/python-list
