TypeError, I know why but not how!?
hat at se-162.se.wtb.tue.nl
Thu Jul 10 08:39:39 CEST 2008
On 2008-07-10, ssecorp <circularfunc at gmail.com> wrote:
> def validate(placed):
> student = round(random.random()*401)
> if student in placed:
> return student, placed
> def pair(incompatibles, placed):
> student1, placed = validate(placed)
> student2, placed = validate(placed)
> pair1 = (student1,student2)
> pair2 = (student2,student1)
> if (pair1 or pair2) in incompatibles:
> pair(incompatibles, placed)
> return pair1, placed
> def generateList(dormlist,incompatibles, placed, rooms):
> if len(dormlist) < (rooms + 1):
> room, placed = pair(incompatibles, placed)
> return dormlist
In each of the above functions, the 'if' part has no 'return', while the 'else'
part has. You should add a 'return' statement at every exit from the function.
If you don't expect the program to get at some point, you should add a check
raise ValueError("This shouldn't happen")
you'd be surprised how often 'impossible' things do happen (and writing such a
statement costs less than a minute, and saves you many hours debugging).
Some people so as far as demanding that there is exactly 1 return statement,
namely at the bottom of the function. While I don't favor that approach, it may
help you in always returning a value.
BTW: For performance and readability, you may want to replace your direct
recursion with iterations.
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