On Wed, Sep 23, 2015 at 12:12 PM, James Harris <james.harri...@gmail.com> wrote: > A list comprehension has various components. Anyone know when each of the > elements is evaluated? In the form > > [v0 for v0 in expr0 if expr1] > > If v0 appears in expr0 or expr1 the evaluation order matters. > > I think of the above as being a rewrite of > > results = [] > for v0 in expr0: > if expr1: > results.append(v0) > return results > > Further, > > [v0, v2 for v0 in expr0 if expr1 for v2 in expr2 if expr3] > > leads to > > results = [] > for v0 in expr0: > if expr1: > for v2 in expr2: > if expr3: > results.append((v0, v2)) > return results > > First of all, is that a correct analog of the list comprehension?
Looks right, see: https://docs.python.org/3/reference/expressions.html#displays-for-lists-sets-and-dictionaries Note that the last sentence there about names not "leaking" is only true for Python 3. You may also be interested in PEPs 202 and 289. -- https://mail.python.org/mailman/listinfo/python-list
