Implementing IEnumerable<t></t>

[Jammer 0]

Hi Again, Any help on this would be really appreciated. Thanks, James.

[buchstaben]

can you tell us why you want to implement your own IEnumerable type? what special functionality is needed? seems like system.collectionn.generic.list would do the job for you.

[Jammer 0]

Hi, Sure, I'm new to C# so bear with me. Basically, my list is eventually going to contain strings, bools, dates, ints, doubles etc ... all sorts basically and I was advised that a generic list would be the way forward and that in order to accommodate those different data types in one list I would need to go down this route ... Also the IEnumerable is required in order to subsequently bind this to an Infragistics datagrid in the application interface. Am I barking up the wrong tree going down this route? Thanks for the reply! James.

[Guffa]

You should implement the IEnumerator for the data type that it should enumerate: class BuildGenericLists : IEnumerable<FileList> You don't have to create an enumerator, the List class already has one that you can return when you implement the GetEnumerator method: return MainFileTableObject.GetEnumerator();

Despite everything, the person most likely to be fooling you next is yourself.

[Jammer 0]

So can a standard List<> hold values of string, int, bool etc at the same time? I was of the impression that a I needed to 'design' my own List<> in order to do this?

[Guffa]

A List<object> can hold any kind of data. You might want to inherit or encapsulate the list and implement some methods to simplify dealing with different objetcs. Another alternative is to create a class that encapsulates an object reference and has methods to handle the different kind of data, and make a list containing items of that class.

Despite everything, the person most likely to be fooling you next is yourself.

[Jammer 0]

Ahhh, OK ... thats good to hear as I've dumped all my old code and started again but I'm having problems with that now ... :( OK here goes again ... I'm still lost on this! I've ditched my old classes and started again, I just couldn't fathom what was wrong or what to do and now I'm having problem with my new implementation. I've written this class:

public class BuildFileList<T> : IEnumerable<T>
{
    private List<T> fileList = new List<T>();

    public T GetFile(int pos)
    {
        return fileList\[pos\];
    }

    public void AddFile(T c)
    {
        fileList.Add(c);
    }

    public void ClearFiles()
    {
        fileList.Clear();
    }

    public int Count
    {
        get { return fileList.Count; }
    }

    IEnumerator<T> IEnumerable<T>.GetEnumerator()
    {
        return fileList.GetEnumerator();
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
        return fileList.GetEnumerator();
    }
}

but using these commands:

BuildFileList<FileList> SingleDirectoryFileStore = new BuildFileList<FileList>();

SingleDirectoryFileStore.AddFile(@"G:\Jammer1\", "2132987KB", ".WAV", "12/12/2001");

Gets two errors:

The type or namespace name 'FileList' could not be found (are you missing a using directive or an assembly reference?)

and

No overload for method 'AddFile' takes '4' arguments

I thought the whole point of using List<T> was that it was generic and you didn't need to tell it in advance what to expect? Man, this whole generics thing has been hurting my head all day, I've not made any progress at all really. Any help on this would be great Guffa I'm completely lost and losing the will to live!

[Elina Blank]

You should specify what is . (This is what Guffa had mentioned to you previously) The generics means, that it will hold just that type of objects, and you do not need to cast it, when getting back. (you were holding objects before Generics)

Sincerely, Elina Life is great!!! Enjoy every moment of it! :-O

[Jammer 0]

Thanks for that! Just 30 seconds before your mail came in I cracked it ... what a painful day! So glad I've now made some progress on this thought, I was starting to go mad with this issue! Thanks for everyone's help and sorry for the daft questions and so on.

[buchstaben]

hm..i'm still not sure if you got it now (looking at the other replies). using a generic collection is mainly useful to have a container with elements of the same type. if you want a list with almost any datatype in it, generics is not helpful. using List list = new List(); will create a list containing only strings. so list.Add will only allow you to add strings and getting elements of this list will always return a string. if all you want is a collection of FileList instances, use List. you will not need to implement ienumerable. if you want a collection of instances of any type, use untyped system.collection.list. you may also want to specify what concrete data you want to hold in that collection, so a better advise can be given.

[Jammer 0]

Hi buchstaben, This is what I have now (got it working last night):

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace SampleSort.DataLayer
{
public class BuildFileList<T> : IEnumerable<T>
{
private List<T> fileList = new List<T>();

    public T Get(int pos)
    {
        return fileList\[pos\];
    }

    public void Add(T c)
    {
        fileList.Add(c);
    }

    public void Clear()
    {
        fileList.Clear();
    }

    public int Count
    {
        get { return fileList.Count; }
    }

    IEnumerator<T> IEnumerable<T>.GetEnumerator()
    {
        return fileList.GetEnumerator();
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
        return fileList.GetEnumerator();
    }
}

public class FileEntry
{
    private string \_fileName;
    private string \_fileSize;
    private string \_fileExt;
    private string \_fileDate;

    public FileEntry(string \_fileName, string \_fileSize, string \_fileExt, string \_fileDate)
    {
        this.\_fileName = \_fileName;
        this.\_fileSize = \_fileSize;
        this.\_fileExt = \_fileExt;
        this.\_fileDate = \_fileDate;
    }

    public string FileName
    {
        get { return \_fileName;}
        set {\_fileName = value;}
    }
    public string FileSize
    {
        get { return \_fileSize; }
        set { \_fileSize = value; }
    }
    public string FileExt
    {
        get { return \_fileExt; }
        set { \_fileExt = value; }
    }
    public string FileDate
    {
        get { return \_fileDate; }
        set { \_fileDate = value; }
    }
}

}

Like I said even though this is only using strings at the moment its going to be expanded to include other value types (bool, ints, double etc...) This is being used by:

    public static List<FileEntry> ScanDirectories(string scanEntryPoint)
    {

        // build the store
        //BuildGenericLists SingleDirectoryFileStore = new BuildGenericLists();
        List<FileEntry> SingleDirectoryFileStore = new List<FileEntry>();

        // grab the start location of the recursion
        DirectoryInfo S

[buchstaben]

in the code you provided, i cant see any use of your class BuildFileList (thats good, since i still believe it is not needed in your case). i've never worked with WPF, but i think i can give you a hint anyway. first, in your button click event handler, dont specify the return value as object. you know it is a List<FileInfo>, so you can use it. to bind this to your ui control, you have to tell the control the bound type. this will be FileEntry, since FileEntry contains the relevant information, not your list. let's take a gridview as user control. Each row will represent a FileEntry, so you need to specify FileEntry as bound type. if you do that at design time, your gridview will autmatically get columns for each property of FileEntry. having this done, simply say myGridView.DataSource = singleDirectoryResults (assuming that singleDirectoryResults is of type List<FileInfo>.

Jammer wrote:

All the binding examples I have seen link into a class (such as BuildFileList) which in my case is an empty definition of an object.

you will need to linke to FileEntry class. hope this is not too weird, since i dont have any dev environment here.

[Jammer 0]

Thanks for this ... I'm just off making some changes and trying a few things you suggest. Thank! :)