[Tutor] calling a superclass method after overriding it

[Alan Gauld]

"Dave Angel" <davea at ieee.org> wrote

>> def result_of_SPECIALIZED_SQLcall_for_child():
>>     name =None
>>     return name

I assume this is a placeholder for more complex code to follow?

>> class Child(Parent):
>>     def add_name(self):
>>         name = result_of_SPECIALIZED_SQLcall_for_child()
>>         try:
>>             name + ''

This does nothing except raise a type error. But that's 
a very contrived way of checking the type.

>>             self.name =ame

I assume this is a typo? And it never gets executed because 
the error is always raised.

>>         except TypeError:
>>             super(Child, self).add_name()

> I know this is a simplified example, but I'd still like to point out 
> that using exceptions when there's a simple test is not reasonable.   
> You can just check for None with a simple if test.

I don't mind using exceptions for a simple test but not where the 
test is being forced by a piece of code that does nothing. In this 
case I agree it would be better to check explicitly for a string if 
a string is required.

Even using exceptions it would be better to do someting like:

try:
   if type(name) != str:
      raise TypeError
   # other stuff here
except TypeError:
    super(....)

It makes the purpose of the code obvious.

But

   if type(name) != str:
        super(....)
   else:
        # other stuff here

is clearer still


-- 
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/