Defining collections-PLEASE HELP 1

[Guest_imported]

Hi,I hope you can help me,coz I'm stuck.
I can't understand some things about defining collections.
Here is an example

public class Animals:CollectionBase
{
public void Add(Animal NewAnimal);
{
List.Add(newAnimal);
}

}

a.How can CollectionBase class implement IList interface if it doesn't implement ALL of IList's methods?How is that possible?

b.List property returns a varible of type IList,which points to an object from which this List property was called from?Right?

c.How can I use List.Add() method if I haven't defined it yet?Where is this method defined?


I hope you will find some time to help me and for that I thank you

 

[chiph]

(a) I haven't gotten that far into writing my own collections (just used the ones provided), but from what I can tell, implementing all the methods provided (specified?) by IList isn't required. I suspect, however, if you fail to provide an implementation of each of them, your code will fail in mysterious ways later on when you try & interact with other parts of the framework.

(b) Don't know.

(c) I think it'll pick up another List method somewhere in the inheritance tree. If you don't like the behavior of this default method, you'll have to provide one yourself.

Chip H.

 

[Guest_imported]

Thank you for your help.But does somebody know the answers?I really need to know this.

Thank you

 

[mgriffith]

if you derive a class from some base, the methods provided by the base are automatically derived as well, unless you override them...then your methods take precedence. c#'s inheritance model is similair to c++'s.

you can see a list of all of the base members (if you're using vs.net) by typing

this.

inside of a function and all of the members of the class will appear in a drop down box.


what i would do would be to do this (sorry if there are spelling/capitalization errors):

public class animallist : CollectionBase
{
//setup the class by calling base constructor and setting innerlist (derived from collectionbase) to a new arraylist
public animallist() : base()
{
this.InnerLIst = new ArrayList();
}
//overloaded construcotr...not necessary
public animallist(ArrayList l) : base()
{
this.InnerList = l;
}

//don't let user see Ilist implementation...force them to use arraylist provided by CollectionBase dervied class (this is actually a 3rd level class)
protected override IList List;

public void Add(animal a) //define this yourself
{
this.InnerList.Add(a); //InnerList is derived property
}

public animal Get(int i)
{
return (animal)this.InnerList; //make the class useful by being able to extract an animal at a certain location in the array
}

//expose the array if you want to be able to do other stuff like searching
public ArrayList animalarray
{
get {
return InnerList;
}
}
}



i hope this helps a little bit mike griffith
----------------------------
mgriffith@lauren.com
mdg12@po.cwru.edu