Suppose that I have function f() that calls g(), I can put a test on the argument 'x' in either g() or f(). I'm wondering what is the common practice.
My thought is that if I put the test in g(x), the code of g(x) is safer, but the test is not necessary when g() is called by h(). If I put the test in f(), then g() becomes more efficient when other code call g() and guarantee x will pass the test even though the test code in not in g(). But there might be some caller of g() that pass an 'x' that might not pass the test, if there were the test in g(). def g(x): # I can put the code here to test whether x satisfies certain conditions. blah, blah def f(x): blah, blah #do something on x # I can also put the code here to test whether x satisfies certain conditions. g(x) def h() blah g(x)#x here are guaranteed to pass the test -- http://mail.python.org/mailman/listinfo/python-list