Indent in Python makes Variable unaccessable

Question

So I have the selfmade class element and I want to create a function, that takes in keyword-arguments which get passed into the constructor of element

It looks like this:

class element:
    def __init__(self, name="element", count=1):
        self.name = name
        self.count = count

def create_element(**kwargs):
    try:
        el = element(**kwargs)
    except TypeError:
        print("You chose arguments which no element has")
    return el

My problem is not that I want a completely different code, but rather to fix the problem I have when I want to return el of the method create_element. If I run this code now, I have a UnboundLocalError, which tells me, that I am accessing a variable before initialing it.

I have tried a finally block, but it had the same result. I see why this is but I don't have a solution.

You're missing the defkeyword before your __init__ That is, your code should say def __init__(self, name = "element", count =1): — Toothpick Anemone
– Toothpick Anemone, Commented Jun 17, 2019 at 14:56
@Toothpick Anemone thanks, just a typing mistake... I will edit it. — by James
– by James, Commented Jun 17, 2019 at 14:57

Adam.Er8 · Accepted Answer · 2019-06-17 15:03:23Z

2

you can define el with a default value outside the try:

class element:
    def __init__(self, name="element", count=1):
        self.name = name
        self.count = count

def create_element(**kwargs):
    el = None
    try:
        el = element(**kwargs)
    except TypeError:
        print("You chose arguments which no element has")
    finally:
        return el

edited Jun 17, 2019 at 15:03

answered Jun 17, 2019 at 14:54

Adam.Er8

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2 Comments

by James Over a year ago

Yeah but what do I do when I want some other Code outside the try-block which doesn't have to be tried? Of course I thought about that but I wanted an other answer, sorry

by James Over a year ago

Thanks, thats the answer I was looking for! I feel so dumb that I couldn't see this on my own, it's so obvious!

Toothpick Anemone · Accepted Answer · 2019-06-17 15:00:37Z

0

You can initialize the return value to some default value before executing the try block:

el = None # initialize return value to default "None"
try:
    el = element(**kwargs)
except TypeError:
    print("You chose arguments which no element has")
return el

Alternatively, move the return statement inside of the try-block

try:
    el = element(**kwargs)
    return el
except TypeError:
    print("You chose arguments which no element has")

answered Jun 17, 2019 at 15:00

Toothpick Anemone

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Comments

Ninad Gaikwad · Accepted Answer · 2019-06-17 15:35:52Z

-1

This is why finally exists in python.

def create_element(**kwargs):
    el = None
    try:
        el = element(**kwargs)
    except TypeError:
        print("You chose arguments which no element has")
    finally:
        return el

edited Jun 17, 2019 at 15:35

answered Jun 17, 2019 at 15:01

Ninad Gaikwad

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2 Comments

Adam.Er8 Over a year ago

here you'd still get UnboundLocalError: local variable 'el' referenced before assignment

Toothpick Anemone Over a year ago

If a type error occurs, then el never gets assigned to. el does not exist. Therefore, the finally block will raise an exception. You can't return el because there is no such thing.

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