override confusing

i have a class like this

Public Class A
Public Overridable Sub F()
End Sub

Public Overridable Sub F(ByVal x As Integer)
End Sub
End Class

i want to inherit a class from Class A like this

Public Class B
Inherits A

Public Overrides Sub F(ByVal x As Integer)
End Sub
End Class

but i get a compile error that says

sub 'F' cannot be declared 'Overrides' because it does not override a sub in a base class.

when i rearrange Class A and change the location of the two overloaded methods it will be ok:

Public Class A
Public Overridable Sub F(ByVal x As Integer)
End Sub

Public Overridable Sub F()
End Sub
End Class

can anybody tell me why it is so?

thankX

That is weird. It seems that the compiler is stopping at the first sub, and not looking further. I don't know if this is by design, or if it is a bug. I will look for an answer, but can't guarantee it.

It must declare the unused overridable function with Overloads and thus requires it on that one was well, because if you add Overloads then it works:

VB Code:

Public Class A
    Public Overridable Sub F()
    End Sub
 
    Public Overridable Sub F(ByVal x As Integer)
    End Sub
End Class
 
Public Class B
    Inherits A
 
    Public [b]Overloads[/b] Overrides Sub F(ByVal x As Integer)
    End Sub
End Class

you need to specify the overloads keywords for those overloaded methods

VB Code:

Public Class A
    Public Overridable Overloads Sub F()
    End Sub
 
    Public Overridable Overloads Sub F(ByVal x As Integer)
    End Sub
End Class
 
Public Class B
    Inherits A
 
    Public Overloads Overrides Sub F(ByVal x As Integer)
    End Sub
End Class

darn..too slow..:-\

Darn it! Edneeis just beat me to that:D
this maybe clearer Edneeis's is also will work perfect.

VB Code:

Public Class A
        Public Overridable Overloads Sub F()
        End Sub
 
        Public Overridable Overloads Sub F(ByVal x As Integer)
        End Sub
    End Class
 
 
 
    Public Class B
        Inherits A
 
        Public Overloads Overrides Sub F(ByVal x As Integer)
 
        End Sub
    End Class

Cander as well:cool:

in Class A you are free to write down Overloads or omit it.
we can always use Overloads Overrides in a derived class if the signature of the method is exactly like the signature of the method in base class. now AGAIN i ask why in the second version of Class A everything is ok (even without Overloads keyword) but in the first version something is wrong?

bug?

:confused:

the problem in your Code exists in Class B since you're trying to inherit Class A which contains 2 Subs with the same Sub names without telling your compiler that you want to overload(making many versions of the same Sub name) the Sub that has the same signature.Class B ,directs the Compiler to inherits Class A.Then , excute next line which is

VB Code:

Public  Overrides Sub F(ByVal x As Integer)
 
End Sub

Now ,the Compiler found that you are inherting the sub called " F " ,he will go to Class A but found 2 Subs have the same names.
in this case, you have to tell your compiler to take care because there are many Subs or Functions have the same name but I want the Sub with this identical signature.So just write Overloads.

Edneeis's way is fine but if you want it more clear , add Overloads keyword to both Subs.

@pirate

so why compiler does not report any error if i write the class like this:

Public Class A
Public Overridable Sub F(ByVal x As Integer)
End Sub

Public Overridable Sub F()
End Sub
End Class

it is all my question about.

You do not have to use the Overloads keyword when you are defining multiple overloaded Subs in the same class. This is only required when inhertiance is applied(from another Class).

@pirate

i am not asking about overloading methods in the same class. what do you mean by saying that? i am asking about a behavior of vb.net compiler about overriding an overloaded method from a base class in a derived class.

in another words........????

in another words i can say

there are 10 kinds of people in the world. those who understand binary and those don't understand binary.

Well , if you can't pose your question in VB.NET language ,it's better you stop programming

@pirate

it was already written in a plain way. if you read it carefully you didnot get a low level machine dependent message.
by the way i assume this is a free of charge site to help people promote their knowledge not to say them quit programming. sooner or later i will get the answer to my PLAIN (not a binary one) question and i will share with those who still go on programming vb.net

Well , I think I expalined everything about Overriding @ Overloading methods , but you need the whole day to understand what I POSTED.If it's difficult to understand then keep away boy!;)

Overriding & Overloading

i tested the two versions of Class A and got that strange compile time error in the first version of Class A and no error in the second one. but in the last one compiler sends a warning message saying method shadowing. i dont know if shadows is the problem or not but i work on it and sent you the result, if any.

daidaluus