Python indentation deters newbies?

[Jeff Shannon]

beliavsky at aol.com wrote:

>You may want to exit a nested loop when testing if a condition involving
>several variables is met, such as searching for a zero of a multivariate
>function. 
>
>In Python you can print i,j,k and exit() when m == 0, but in a larger program
>you may want more control.
>  
>

In this case, I can see several Pythonic ways of doing this.

One would be to use an exception.  While exceptions are not considered 
good control structures in other languages, they *are* considered 
acceptable (and even desirable) in Python.

Another way would be to wrap the nested loops inside a function, and 
simply return the appropriate triple from that function as soon as you 
find it.

An improvement on that would be to replace your return statement with a 
yield.  Suddenly you've got a generator that'll find a whole series of 
Pythagorean triples!

def pyth_triple(max):
    max += 1   # to simplify range() calls later
    for i in range(1,max):
        for j in range(1,max):
            ij = i**2 + j**2
            for k in range(1,max):
                m = ij - k**2
                if m == 0:
                    yield (i, j, k)

for triple in pyth_triple(10):
    print triple
(3, 4, 5)
(4, 3, 5)
(6, 8, 10)
(8, 6, 10)

For my money, that's cleaner/clearer than the Fortran version.

Jeff Shannon
Technician/Programmer
Credit International