[Edu-sig] teaching Python
mark.engelberg at alumni.rice.edu
Fri Apr 23 19:44:00 CEST 2010
They have every right to be confused. Who would guess that Python
evaluates optional arguments once at compile-time? Heck, I've used
Python for years and I wouldn't have been able to tell you off the top
of my head how Python handles this code.
That reminds me of a similar gotcha I've unfortunately run into on
more than one occasion.
# intialize a to be a list of 5 empty lists
a = 5*[]
# push a value onto the first list.
(P.S. Stuff like this drives me nuts, which is why I find myself
gravitating more and more to languages with a richer set of immutable
data structures, e.g., Clojure/Scala/etc., where both of these gotchas
would become a non-issue. I would love to see more immutable
datatypes in Python other than numbers/strings/tuples, although
realistically, I'd say that's unlikely to happen.)
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