how to find type of object

  • Thread starter Thread starter buller
  • Start date Start date
Correct.  A square is not an extension of a rectangle, it is a constraint on
a rectangle, so making Square derived from Rectangle is bad.  Not all
rectangles are squares, so making Rectangle derived from Square is very bad.
Click to expand...

Well, I don't think deriving Square from Rectangle is necessarily
bad. At least a square is a rectangle and had the blogger done the
derivation in that direction I wouldn't be beating down his argument.
Maybe that's the subject of another debate though.
 
It looks to me like everyone missed the actual question here. Maybe we can
change this to:

private class A {}
private class B : A {}
private class C : B {}

// this is what you want I think:
if (list.GetType() == typeof(B))

The problem with this is that it is probably pretty slow. One thing you
could do is define an enum that add a property to A and then the children can
override it.

private enum FigureType { Unknown, Square, Rectangle, Circle }

private class A {
public virtual FigureType FigureType { get { return FigureType.Unknown; } }
}

private class B {
public override FigureType FigureType { get { return FigureType.Square; } }
}

private class C {
public override FigureType FigureType { get { return FigureType.Rectangle; } }
}

//....

if (list.FigureType == FigureType.Square)

This will just be a virtual method call.
 
Bryan said:
It looks to me like everyone missed the actual question here. Maybe we
can
change this to:

private class A {}
private class B : A {}
private class C : B {}

// this is what you want I think:
if (list.GetType() == typeof(B))
Click to expand...


That's exactly what Peter suggested about four weeks ago.
The problem with this is that it is probably pretty slow. One thing you
could do is define an enum that add a property to A and then the children
can
override it.

private enum FigureType { Unknown, Square, Rectangle, Circle }
Click to expand...

That isn't extensible.
private class A {
public virtual FigureType FigureType { get { return
FigureType.Unknown; } }
}

private class B {
public override FigureType FigureType { get { return
FigureType.Square; } }
}

private class C {
public override FigureType FigureType { get { return
FigureType.Rectangle; } }
}

//....

if (list.FigureType == FigureType.Square)

This will just be a virtual method call.
Click to expand...
 
It looks to me like everyone missed the actual question here.  Maybe wecan
change this to:
Click to expand...

I knew exactly what the question was. I choose to provide alternate
way of looking at the situation that made the question moot.
 
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