On 24.02.2017 01:19, Irv Kalb wrote:
Hi,
I have built a set of three classes:
- A super class, let's call it: Base
- A class that inherits from Base, let's call that: ClassA
- Another class that inherits from Base, let's call that: ClassB
ClassA and ClassB have some code in their __init__ methods that set some
instance variables to different values. After doing so, they call the the
__init__ method of their common super class (Base) to set some other instance
variables to some common values. This all works great. Instances of ClassA
and ClassB do just what I want them to.
[...]
If I can find a way to determine that the caller is attempting to instantiate
Base directly, I will raise an exception.
A pattern I'm using sometimes to achieve this is:
class Base:
def __init__(self):
self.set_common()
self.set_specific()
def set_common(self):
self.a = 10
def set_specific(self):
raise NotImplementedError()
class A(Base):
def set_specific(self):
self.b = 20
class B(Base):
def set_specific(self):
self.b = 30
Of course, MRAB's and Peter's suggestion are very similar ideas.
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