can a function return twice inside a for loop statement

Question

I have the following function that check whether a regex input is legit:

import re

def isvalid_regex():
    for _ in range(2):
        try:
            re.compile(input())
            return True
        except re.error:
            return False

The problem here is that I don't get a double input as I would expect by range(2). The function returns me False or True and exits. I guess a function cannot repeat return statements for the number of times of a for loop in range(x) exists right ? My goal is to have a double input and a double True or False return. For example as output:

True
False

Answer 1

return statement ends the function.
You have two options:

1. generator

You can learn about generator in: https://docs.python.org/3/howto/functional.html?#generators

def isvalid_regex():
    for _ in range(2):
        try:
            re.compile(input())
            yield True
        except re.error:
            yield False


for x in isvalid_regex():
    print(x)

input and output:

t
True
\\\
False

2. Build a list and return once

def isvalid_regex():
    results = []
    for _ in range(2):
        try:
            re.compile(input())
            results.append(True)
        except re.error:
            results.append(False)
    return results


for x in isvalid_regex():
    print(x)

input and output:

t
\\\
True
False

Note:

You might noticed that the order of execution is different. You can choose what fits your situation.

Answer 2

It is not clear what you want to do.

Functions do return only once, but they can return sequences, so you could use that "trick" for returning multiple values.

For example:

a = [1, 2]


def squarer(items):
    return [item ** 2 for item in items]


print(squarer(a))
# [1, 4]

---

If you want to exit from a function multiple times but then come back to its internal state (for convenience) then you should use a generator. To do so, you replace the return statement with a yield one. With this method, once a yield statement is reached, you get a value. Subsequent values from the generator can be obtained with next() or by using the generator in a for loop.

For example:

def squarer(item):
    for x in range(item):
        yield x ** 2


itr = squarer(4)
# <generator object squarer at 0x7f145c421eb8>
print(itr)
for x in itr:
    print(x)
# 0
# 1
# 4
# 9