Solved

clone of an inherited generic list

Posted on 2010-08-27
5
724 Views
Last Modified: 2013-11-08
I have a class "NavigationElement", where I implemented a clone method.

Then I have a generic List that inherits from a list of this objects (NavigationElement)

public class NavigationElementsList<NavigationElement> : List<NavigationElement>, ICloneable
...
in this list I also implemented the
   public Object Clone()
        {
            return this.MemberwiseClone();
        }

now I need to call the FindAll method in an istance of this NavigationElementsList<NavigationElement>, but this is not possible because the returned type is not the same as the generic List<T>.
I need to have a deep copy of the list because I'm going to change the values of the properties and this will cause a change in the referenced items in  the original list<T> that I want to avoid.

This also won't work:
 public NavigationElementsList<T> FindAll(Predicate<T> match)
        {
            return base.FindAll(match);
        }

Any suggestions?
0
Comment
Question by:LorenzoB
  • 3
5 Comments
 

Author Comment

by:LorenzoB
ID: 33543064
Actually resolved in this way (maybe useful for some other).
 public NavigationElementsList<NavigationElement> FindAll(Predicate<NavigationElement> match)
        {
            NavigationElementsList<NavigationElement> navCopyOfList = new NavigationElementsList<NavigationElement>();
            navCopyOfList.AddRange(base.FindAll(match));
            return navCopyOfList;
        }
0
 
LVL 30

Expert Comment

by:MlandaT
ID: 33543074
0
 

Author Comment

by:LorenzoB
ID: 33543110
The problem is in the FindAll method and the type that it returns.
Thank you anyway
0
 
LVL 8

Accepted Solution

by:
Gururaj Badam earned 500 total points
ID: 33579507
In the first place why do you want to inherit from List<T>. I suggest you to write an extension method instead to add your clone method

say like

public T Clone<T>(this List<T> _list)
        {
            return _list.MemberwiseClone(); // Or something like this
        }
0
 

Author Comment

by:LorenzoB
ID: 33581765
To answer to your question, I needed to Inherit from a List<T> because I want to have the FindAll and the Clone (DeepCopy not Shallow).

Your suggestion was indeed helpful.

MemberwiseClone() cannot be called by an extension method of a generics list because it is a private member.
So I did a sort of implementation of the MemberwiseClone.
In the following extract of code are the Extension methods. Maybe could be better written...
The class NavigationElement inherits from ICloneable and implements the Clone() method.

In this way I avoid to create a new Class that inherits from List<NavigationElement>, because the implementation of the Extension Methods.

Thank You
 public static class ListExtensions
        {
            public static object Clone<T>(this List<NavigationElement> list)
            {
                return list.MemberwiseClone<T>();               
            }

            public static List<NavigationElement> MemberwiseClone<T>(this List<NavigationElement> list)
            {
                List<NavigationElement> newList = new List<NavigationElement>();
                foreach (NavigationElement navElem in list)
                {
                    newList.Add((NavigationElement)navElem.Clone());
                }
                return newList; 
            }
        }

Open in new window

0

Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

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

We all know that functional code is the leg that any good program stands on when it comes right down to it, however, if your program lacks a good user interface your product may not have the appeal needed to keep your customers happy. This issue can…
This document covers how to connect to SQL Server and browse its contents.  It is meant for those new to Visual Studio and/or working with Microsoft SQL Server.  It is not a guide to building SQL Server database connections in your code.  This is mo…
This video shows how to use Hyena, from SystemTools Software, to bulk import 100 user accounts from an external text file. View in 1080p for best video quality.

856 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