Steven D'Aprano wrote:
> I came across an interesting (as in the Chinese curse) problem today. I
> had to modify a piece of code using generator expressions written with
> Python 2.4 in mind to run under version 2.3, but I wanted the code to
> continue to use the generator expression if possible.
>
> My first approach was to use a try...except block to test for generator
> expressions:
>
> try:
> gen = (something for x in blah)
> except SyntaxError:
> def g():
> for x in blah:
> yield something
> gen = g()
>
>
> This failed to work under 2.3, because the SyntaxError occurs at compile
> time, and so the try block never happens.
>
> I've been burnt by making assumptions before, so I tried a second,
> similar, approach:
>
> if sys.version_info >= (2, 4):
> gen = (something for x in blah)
> else:
> # you know the rest
>
> As expected, that failed too.
>
> The solution which worked was to put the generator expression in a second
> module, then import that:
>
> try:
> import othermodule
> except SyntaxError:
> # fall back code
>
>
> What techniques do others use?
>
>
Here is one every one will have fun lambasting:
try:
exec('gen = (something for x in blah)')
except:
def g():
# etc.
James
--
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095
http://www.jamesstroud.com/
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