returning out of for-loop

Question

I'm pretty new at python and I was wondering if this:

def func(self, foo):
    for foo in self.list:
        if foo.boolfunc(): return True
    return False

is good practice.

Can I return out of a loop like the above or should i use a while-loop, like so?

def func(self, foo):  
    found = false
    while(not found & i < len(self.list)):
        found = foo.boolfunc()
        ++i
    return found

My java-professor warns us never to use breaks in our loops, but this technically isn't a break and it's more concise, so... yeah

thanks

Answer 1

There's nothing wrong with your example, but it's better to write

def func(self, foo):
    return any(foo.boolfunc() for foo in self.list)

Answer 2

It should be mentioned that in Python, for loops can have an else clause. The else clause is only executed when the loop terminates through exhaustion of the list.

So you could write:

def func(self):
    for foo in self.list:
        if foo.boolfunc():
            return True
    else:
        return False

Answer 3

Your professor is advocating a practice called "Single point of Return", which basically states that any block of code should only have one point of exit. Breaks in loops are somewhat distinct from this, but usually lumped together.

It's a controversial opinion, to say the least, and certainly not as hard and fast a rule as "never use goto". It's probably worth doing it his way - you can appease him and also see the benefit of both approaches, but most people probably aren't too strict on single point of return if violating it makes their code more readable.