Why does IEnumerable<char> ToString() work in xamarin android?-CodePudding

~~In C# you cannot override the ToString() method of an IEnumerable.~~ It's polymorphism what I missed.

Therefore this

IEnumerable<char> chars = new List<char> { 'a', 'b', 'c' };
chars.ToString();

doesn't give me "abc".

Looking into some Xamarin.Android I wonder how the following converts into the correct string:

//In OnCreate
FindViewById<EditText>(Resource.Id.txt_username).TextChanged  = GenerateNewPassword;


//my method
private void GenerateNewPassword(object sender, Android.Text.TextChangedEventArgs e)
{
    passwordView.Text = e.Text.ToString();
}

What am I missing, why does this work?

CodePudding user response：

The ToString override is coming from the underlying type, not the IEnumerable<T>. I'm not sure how Xamarin is providing that exactly, but I presume it is a custom type that implements IEnumerable<T>. For example, we can do this:

public class MyList<T> : List<T>
{
    public override string ToString()
    {
        return string.Join("", this);
    }
}

And now we can do this:

IEnumerable<char> chars = new MyList<char> { 'a', 'b', 'c' };
Console.WriteLine(chars.ToString());

Which will output:

abc