def foo(x): if x >= 0: return math.sqrt(x)">

(original) (raw)

I've taken the liberty of adding the following old but good rule to PEP 8 (I was surprised to find it wasn't already there since I've lived by this for ages):

Be consistent in return statements. Either all return statements in a function should return an expression, or none of them should. If any return statement returns an expression, any return statements where no value is returned should explicitly state this as return None, and an explicit return statement should be present at the end of the function (if reachable).
Yes:
```
def foo(x):  
 if x >= 0:  
 return math.sqrt(x)  
 else:  
 return None

def bar(x):
 if x < 0:
 return None
 return math.sqrt(x)
```
No:
```
def foo(x):
 if x >= 0:
 return math.sqrt(x)
def bar(x):
 if x < 0:
 return
 return math.sqrt(x)
```

--

--Guido van Rossum (python.org/~guido)