[Tutor] Basic class inheritance

[Kent Johnson]

Negroup - wrote:
> I have this class:
> 
>>>>class A:
> 
> ...     def __init__(self, blank=False, editable=True, name='foo'):
> ...             self.blank = blank
> ...             self.editable = editable
> ...             self.name = name
> ...
> 
>>>>a = A()
>>>>a.blank, a.editable, a.name
> 
> (False, True, 'foo')
> 
> All as expected.
> 
> Now I want that another class, call it B, inherits all
> behaviours/attributes except for the attribute blank, that now I want
> to be False.
> 
> This should be possible overriding __init__ method no? 
> 
>>>>class B(A):
> 
> ...     def __init__(self, blank=True, editable=True, name='foo'):
> ...             self.blank = blank
> ...             self.editable = editable
> ...             self.name = name
> ...
> 
>>>>b = B()
>>>>b.blank, b.editable, b.name
> 
> (True, True, 'foo')	
> 
> However, is it possible to achieve this without rewrite the whole
> __init__ method, but just overriding parts of it?

The usual way to do this is to forward to the __init__() method of the superclass for the common part. In your case you are just specializing the default arguments so all you have to do is pass the args to A.__init__():

class B(A):
  def __init__(self, blank=True, editable=True, name='foo'):
    A.__init__(self, blank, editable, name)

Kent