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Bonus Points

You can get can get bonus points here for changing these functions to compute the maximum, rather than minimum, values. This one’s easy: the first two versions only require changing < to >, and the third simply requires that we return tmp[−1] instead of tmp[0]. For an extra point, be sure to set the function name to “max” as well (though this part is strictly optional).

It’s also possible to generalize a single function to compute either a minimum or a maximum value, by evaluating comparison expression strings with a tool like the eval built-in function (see the library manual) or passing in an arbitrary comparison function. The file minmax.py shows how to implement the latter scheme:

def minmax(test, *args):
    res = args[0]
    for arg in args[1:]:
        if test(arg, res):
            res = arg
    return res

def lessthan(x, y): return x < y                # See also: lambda
def grtrthan(x, y): return x > y

print(minmax(lessthan, 4, 2, 1, 5, 6, 3))       # Self-test code
print(minmax(grtrthan, 4, 2, 1, 5, 6, 3))

% python minmax.py
1
6

Functions are another kind of object that can be passed into a function like this one. To make this a max (or other) function, for example, we could simply pass in the right sort of test function. This may seem like extra work, but the main point of generalizing functions this way (instead of cutting and pasting to change just a single character) is that we’ll only have one version to change in the future, not two.