Style Guide for Python Code (PEP 8)

[cawaltrip]

Here is the Style Guide for Python Code. It's a rather easy read, with code snippets as examples throughout the entire thing.

[hallister]

In the meeting yesterday I mentioned "never asking for permission" in Python. There are two python methods below, one is the "Pythonic" way of doing things, the other isn't.

Note: the methods below can return invalid values (-2/0 will return infinity) so don't use it.

def pDivide(x, y):
    try:
        return  x / y
    except ZeroDivisionError:
        return float('inf')
   finally: 
        return None

def cDivide(x,y):
    if (y > 0):
         if(isinstance(x/y, (float,int,long,complex)):
            return x/y
         else: 
             return None
    else:
        return float('inf')

For the most part these do the same thing (there are caveats, since the second example won't catch Exceptions).

The first example is clean, and clear. What it's doing is:

• Attempt to divide x by y.
• If that fails because y = 0, return infinity.
• If that fails for any other reason, return None.

The lesson here: ALWAYS try fail over type/value checking. Here's a full try block:

try:
    test = a / b
except ZeroDivisionError:
    print "Can't divide by zero."
else:
    print "The value is ", test
finally:
    print "An unknown exception occurred"

[cawaltrip]

Closed due to being moved to the wiki: Style Guide