Understanding Python bytecode by implementing tail call optimization

12 points by mynameisfiber 11 years ago | 3 comments

hughdbrown 11 years ago |

This code does not do what the author thinks it does:

    def factorial(N, result=1):
        if N == 1:
            return 1
        return factorial(N-1, N*result)

mynameisfiber 11 years ago | |

No, but the time complexity is the same.

hughdbrown 11 years ago | | |

Okay but if you are going to call the function factorial, why not have it actually calculate a factorial? This would have done the job:

    def factorial(N, result=1):
        if N == 1:
            return result
        return factorial(N-1, N*result)

Assuming that you never call it with the result argument.

As written, it just looks like the author never ran the code.