[ACCEPTED]-Can you inherit a sub new (Constructor) with parameters in VB?-new-operator

Accepted answer
Score: 60

The behavior that you are seeing is "By 22 Design". Child classes do not inherti 21 constructors from their base types. A child 20 class is responsible for defining it's own 19 constructors. Additionally it must ensure 18 that each constructor it defines either 17 implicitly or explicitly calls into a base 16 class constructor or chains to another constructor 15 in the same type.

You will need to define 14 the same constructor on all of the child 13 classes and explicitly chain back into the 12 base constructor via MyBase.New. Example 11

Class ChildClass
  Inherits BaseClass
  Public Sub New(text As String)
  End Sub
End Class

The documentation you are looking for is 10 section 9.3.1 of the VB Language specification.

I 9 think the most relevant section is the following 8 (roughly start of the second page)

If a type 7 contains no instance constructor declarations, a 6 default constructor is automatically provided. The 5 default constructor simply invokes the parameterless 4 constructor of the direct base type.

This 3 does not explicitly state that a child class 2 will not inherit constructors but it's a 1 side effect of the statement.

Score: 9

Parameterized Constructors cannot be inherited 7 in the same way as instance methods. You 6 need to implement the constructor in the 5 child class and then call the parent's constructor 4 using MyBase.

Public Class ChildClass
    Inherits BaseClass

    Public Sub New (ByVal SetText As String)
    End Class
End Class

Public Class TestClass
  Public TestChild AS New ChildClass("c")
End Class

This limitation is not VB specific. From 3 what I can gather, it's definately not possible 2 in C#, Java or C++ either.

Here is one related 1 post with the same question about C++:

More Related questions