Re: [Python-ideas] Accessing the result of comprehension's expression from the conditional

On Fri, Jun 19, 2009, Lie Ryan wrote:

In list/generator comprehension, currently we have no way to access the result of the expression and have to write something like this:

[f(x) for x in l if f(x) > 0]

if f() is heavy or non-pure (i.e. have side effects), calling f() twice might be undesirable.

Listcomps and genexps are like lambdas: run up against their limits and you should switch to a regular for loop or generator. -- Aahz (aahz@pythoncraft.com) <*> http://www.pythoncraft.com/ "as long as we like the same operating system, things are cool." --piranha