C# put methods in different class.

techguy

Hi,

Ok, so in VB.NET i've been using a library (TwitterVB) that has put different methods in different classes. How do I do this in C# ?

Sample Code:

public class Parent
{
[INDENT]public void mParent()
{
}[/INDENT]
}
public class Child : Parent
{
[INDENT]public void mChild()
{
}[/INDENT]
}

Is this possible?:

Parent obj = new Parent();
obl.Child.mChild();

I would think this is possible if obj was of type Child. I'm sure i'm missing out on the use of some OOP keyword or something.

Ideas?

stevenmu

It's possible yes. The way you would do it depends on exactly what you want to achieve.

You also need to consider "is a" and "has a" relationships and maybe get a better understanding of inheritance. In your example you have defined Child as inheriting from Parent (i.e. Child "is a" Parent). In this case Child would inherit any methods in Parent, for e.g. the mParent() method.

Then typically you would create an instance of the Child

Child myChild = new Child();

and you could call methods in both it and the parent

myChild.mChild();
myChild.mParent();

What you have described in the line "obl.Child.mChild();" is more of a "has a" relationship. For this you would define your classes differently for e.g.

public class Class1
{
   public Class2 myObj2;

   public Class1()
   {
      this.myObj2 = new Class2();
   }
}

public class Class2
{
   public void method2()
   {
      //do something
   }
}

Now Class1 has an instance of Class2 and you can call methods like you described in your example, myObj2 is a property of class 1 and can be referenced from it.

Class1 myObj = new Class1();
myObj.myObj2.method2();

Hope that makes sense?

techguy

stevenmu wrote: »

Hope that makes sense?

Yes, it does. Thanks.

I understand inheritane and all that but I still couldn't do what I wanted.

I had thought of creating a Class2 object in Class1 and calling that to access class2 but I wasn't sure it was the right way of doing it.

At least now I know somebody else approves of this technique so i'll happily use it.

Thanks!

stevenmu

Yep, it's a reasonably standard thing to do.

One additional suggestion: in my example I just made myObj2 public in Class1 which allows it to be accessed from other classes. While this works fine, it's not considered best practice, the best practice way is to make it private and to use Properties to access it, the benefit of these is that it allows you to put extra logic in (like in the example on the MS site where instead of just returning the seconds it converts them to hours). But certainly just for experimenting/learning leaving it public and accessing it directly is fine.

techguy

Yes, I have been looking at that also. Thanks.

I'm getting a StackOverflowException now when I try and create a new object of the dervied class in the parent.

I'm thinking this is caused by an infinit loop but I can't see where.Annoying!

EDIT: The loop is caused by specifying that the child class is inheriting from the parent.
I am declaring a new instance of child in the default constructor for parent.
How can I solve this while keeping the inheritance intact?

EDIT Again: I ave viewed a class diagram for TwitterVB and it appears that all the method classes are tied together using a methodsBase class.

I suppose it's about time I sitdown with a pen and paper..:o