[Python-Dev] 2.5 and beyond (original) (raw)

Terry Reedy tjreedy at udel.edu
Sat Jul 1 06:27:16 CEST 2006

"Giovanni Bajo" <rasky at develer.com> wrote in message news:020c01c69ca1$754c7310$d1b12997 at bagio...

Yes but:

a = [] for i in range(10): ... a.append(lambda: i) ... print [x() for x in a] [9, 9, 9, 9, 9, 9, 9, 9, 9, 9] This subtle semantic of lambda is quite confusing, and still forces people to use the "i=i" trick.

The 'subtle sematic' had nothing to do with lambda but with Python functions.

The above is exactly equivalent (except the different .funcname) to

a = [] for i in range(10): def f(): return i a.append(f) del f

That should be equally confusing (or not), and equally requires the 'i=i' trick (or not).

As is, either function definitiion is a constant and the loop makes useless duplicates. Either form would have the same effect is hoisted out of the loop.

Terry Jan Reedy

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