why can't i use () behind except in Python2.7?

Question

I have the following code - I've commented next to the line where I don't understand the results.

class A:
    pass;
class B(A):
    pass;
class C(B):
    pass;

for i in [A,B,C]:
    try:
        raise i();
    except C:
        print("C");
    except B:
        print("B");
    ### if i write A(), it shows: __main__.A: <__main__.A instance at 0x00ACBE18>
    except A:
        print("A");

This is my first time using the site, so please let me know if anything requires clarification...

Answer 1

A is a class. when you write A() you actually instantiate the class A

When you raise an instance of class A as an exception (when i = A), there is no except clause that will catch this instance when it is written like this A()

So what that you see: __main__.A: <__main__.A instance at 0x00ACBE18> is the instance that has been raise and no one catches it.

You actually can use () in. try it on C().

class A: 
    pass
class B(A): 
    pass 
class C(B):
    pass

for i in [A,B,C]: 
    try: 
        raise i()
    except C(): 
        print("C")
    except B:
        print("B")
    except A:
        print("A")

Will output:

A
B
B

You can read more about errors and exceptions in python here.