Override IEnumerable Where

Question

I\'ve written a class that implements IEnumerable :

public class MyEnumerable : IEnumerable
{ 
    IEnumerator IEnumerable.GetEnumerator()
    {
         


        

Answer 1

Update

From your comment your enumerator is a lazy file enumerator and you want to be able to select items from it based on a predicate and still have the laziness.

You could create another class inheriting that class or an interface to help with this.

Here is an example

public class FileItem
{
    //Some properties
}

public interface IFileEnumerator : IEnumerable
{
    IFileEnumerator Where(Func predicate);
}

public class FileEnumerator : IFileEnumerator
{
    private readonly string fileName;

    public FileEnumerator(string fileName)
    {
        this.fileName = fileName;
    }

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

    public IEnumerator GetEnumerator()
    {
        var items = new List();

        //Read from file and add lines to items

        return items.GetEnumerator();
    }

    public IFileEnumerator Where(Func predicate)
    {
        return new MemoryEnumerator(ToEnumerable(GetEnumerator()).Where(predicate));
    }

    private static IEnumerable ToEnumerable(IEnumerator enumerator) 
    {
        while (enumerator.MoveNext()) 
        {
            yield return enumerator.Current;
        }
    }
}

public class MemoryEnumerator : IFileEnumerator
{
    private readonly IEnumerable items;

    public MemoryEnumerator(IEnumerable items)
    {
        this.items = items;
    }

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

    public IEnumerator GetEnumerator()
    {
        return items.GetEnumerator();
    }

    public IFileEnumerator Where(Func predicate)
    {
        return new MemoryEnumerator(items.Where(predicate));
    }
}