Solved

How do you declare a "MustOverride" Constant?

Posted on 2010-11-15
6
904 Views
Last Modified: 2012-05-10
Okay, I'm painfully new to TRUE OOP programming, and am working with inheritance.  I have a constant that I want each child class to be forced to set, so that in the base class a common method can be run that uses the value as set by its children.

I've tried the following:

Protected MustOverride Const Foo As Long

But needless to say, VB.Net no likey.  

I've come to the conclusion that I can create a regular variable in the base class, then make a required sub that "sets" the value of the variable, but this definitely feels like a hack.

Suggestions?
0
Comment
Question by:Javin007
  • 3
  • 3
6 Comments
 
LVL 4

Author Comment

by:Javin007
ID: 34140955
Update:  I've now found that I can make a "MustInherit" ReadOnly Property, but that still also feels hackish.
0
 
LVL 75

Accepted Solution

by:
käµfm³d   👽 earned 500 total points
ID: 34140963
You can declare a MustOverride ReadOnly property on your base class (and define the class as MustInherit). Then, in your child class, implement the property. Here is an example:
Public MustInherit Class BaseClass
    Public MustOverride ReadOnly Property Foo() As Long
End Class



Public Class Child1
    Inherits BaseClass

    Private Const _foo As Long = 10

    Public Overrides ReadOnly Property Foo() As Long
        Get
            Return _foo
        End Get
    End Property
End Class

Open in new window

0
 
LVL 4

Author Comment

by:Javin007
ID: 34145821
Bummer.  This is considered the "right" way to do it?
0
3 Use Cases for Connected Systems

Our Dev teams are like yours. They’re continually cranking out code for new features/bugs fixes, testing, deploying, testing some more, responding to production monitoring events and more. It’s complex. So, we thought you’d like to see what’s working for us.

 
LVL 75

Assisted Solution

by:käµfm³d 👽
käµfm³d   👽 earned 500 total points
ID: 34147162
AFIK, yes, because MustOverride only applies to properties and procedures. You are still accomplishing the same goal provided you keep the ReadOnly keyword in there. Of course, it wouldn't make sense to have a "setter" point to a const private member anyways!
0
 
LVL 75

Assisted Solution

by:käµfm³d 👽
käµfm³d   👽 earned 500 total points
ID: 34147172
P.S.

This isn't necessarily a restriction of OOP--more likely it is a restriction of VB.NET.
0
 
LVL 4

Author Closing Comment

by:Javin007
ID: 34148705
Thanks!
0

Featured Post

Master Your Team's Linux and Cloud Stack

Come see why top tech companies like Mailchimp and Media Temple use Linux Academy to build their employee training programs.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In my previous article (http://www.experts-exchange.com/Programming/Languages/.NET/.NET_Framework_3.x/A_4362-Serialization-in-NET-1.html) we saw the basics of serialization and how types/objects can be serialized to Binary format. In this blog we wi…
This article describes relatively difficult and non-obvious issues that are likely to arise when creating COM class in Visual Studio and deploying it by professional MSI-authoring tools. It is assumed that the reader is already familiar with the cla…
This tutorial gives a high-level tour of the interface of Marketo (a marketing automation tool to help businesses track and engage prospective customers and drive them to purchase). You will see the main areas including Marketing Activities, Design …
Although Jacob Bernoulli (1654-1705) has been credited as the creator of "Binomial Distribution Table", Gottfried Leibniz (1646-1716) did his dissertation on the subject in 1666; Leibniz you may recall is the co-inventor of "Calculus" and beat Isaac…

776 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question