Possible to call methods 2 levels up the inheritence tree possible(not just 'MyBase.X()')

  • Thread starter Thread starter Jack
  • Start date Start date
J

Jack

Hello,

I have a 3-level class hirarchy:

1=Grandparent
2=Parent
3=Child

The Grandparent has a method called OnPaint which I want to override
from the Child class. I can do this, but how can I call the
Grandfather's OnPaint() method inside this newly overrided one in the
child class.

I can't use: MyBase.OnPaint(..) because it expects the OnPaint(...) to
be in the Parent class immediately above.

How can call a method from a class 2 levels further up from this child
class? I'm playing with creating custom winform controls if you were
wondering.

Thanks,
Jack.
 
I can't use: MyBase.OnPaint(..) because it expects the OnPaint(...) to
be in the Parent class immediately above.
Click to expand...

No it doesn't. If there's no OnPaint override in Parent then the
implementation in Grandparent will be called.


Mattias
 
Jack said:
I have a 3-level class hirarchy:
Click to expand...
1=Grandparent, 2=Parent, 3=Child
Click to expand...
The Grandparent has a method called OnPaint which I want to override
from the Child class. I can do this, but how can I call the
Grandfather's OnPaint() method inside this newly overrided one in the
child class.
Click to expand...

Move the important code sideways into another, Protected method.
Have the [Grandparent].OnPaint call this new method.

The Parent can do what it likes, overriding OnPaint or not.
You don't actually care.

[Child].OnPaint will override anything in [Grandparent].OnPaint or
[Parent].OnPaint, unplugging their respective implementations and
replacing it with its own.
[Child].OnPaint /can/ call your extracted method, thereby bypassing the
Parent level entirely.
I can't use: MyBase.OnPaint(..) because it expects the OnPaint(...) to
be in the Parent class immediately above.
Click to expand...

If there's an implementation of [Parent].OnPaint, then MyBase.OnPaint
will use that. If there /isn't/, then it will "cascade" up into
[grandParent].OnPaint. Of course, you have no way of knowing which.
How can call a method from a class 2 levels further up from this child
class?
Click to expand...

With multiple, possible overrides involved, you can't.

HTH,
Phill W.
 
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