Nested try/except statement for method

Question

I wonder if it is possible to handle the exceptions raised when calling a method via a function (this is necessary as in the production code different objects are created depending on args passed) as in the following example.

Function createObj triggers the creation of an object Obj_A based off different criteria and is supposed to handle any exceptions that may occur with Obj_A.

def createObj():
    try:
        return Obj_A()                
    except:
        print("Bad boy!")

Obj_A has a method that creates a nested object, in which I would like to catch exceptions and handle those at the level of createObj:

class Obj_A(object):
    def __init__(self):
        pass

    def myFunc(self, var):
        return self.Obj_B(self, var)

    class Obj_B(object):
        def __init__(my, self, var):
            try:
                1/0
            except:
                raise ValueError("Don't divide by zero")

Calling createObj works just fine. But calling createObj.myFunc('var') raises the ValueError("Don't divide by zero").

Of course, handling the error on a

try:
    createObj().myFunc('var')
except:
    print("Not what I need")

would work, but is unfortunately not desirable for this use case.

Is there a way to handle this exception on the createObj level and return Bad boy!?

Asked By: braunlee

||

Source

Answer 1

You want to handle an exception with the except clause that will be raised in the future after the corresponding try statement. It’s impossible, and unnatural if it’s possible.

Instead, do in other way like this example.

def createObj():
    def handle_exception(e):
        print("Bad boy!")
    return Obj_A(handle_exception)

class Obj_A(object):
    def __init__(self, handle_exception):
        self.handle_exception = handle_exception

    def myFunc(self, var):
        try:
            return self.Obj_B(self, var)
        except Exception as e:
            self.handle_exception(e)

Answered By: relent95

Nested try/except statement for method

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