C# Generic Multiple Parameters

Question

I have a generic method that has several parameters plus a return type:

    public static class Support
{
    public static TR JSONKeyName<TR, T1, T2, T3>(this IEnumerable<Tuple<T1, T2>> a, Action<T3> b)
    {
        TR result = default(TR);

        try
        {
            foreach (var entry in a)
            {
                b((T3)TypeDescriptor.GetConverter(typeof(T3)).ConvertFromInvariantString("[ \"" + entry.Item1 + "\", " + entry.Item2 + "\" ]"));
            }

            result = (TR)Convert.ChangeType(true, typeof(TR));
        }
        catch
        {
            result = (TR)Convert.ChangeType(false, typeof(TR));
        }

        return result;
    }
}       


List<Tuple<int, string>> list = new List<Tuple<int, string>>();
list.Add(new Tuple<int, string>(1, "Test 1"));
list.Add(new Tuple<int, string>(2, "Test 2"));
list.Add(new Tuple<int, string>(3, "Test 3"));

var res = list.JSONKeyName<bool>((string entry) =>
    {


    });

When calling JSONKeyName from the example above I get the following error:

The compiler error is:

*Using the generic method requires 4 type arguments

The method has 4 type parameters, so it requires 4 type arguments... where is the confusion? — Paul Bellora
– Paul Bellora, Commented Mar 7, 2013 at 5:33
I understand what the error is saying. But one of the parameter is for the return type which is TR. So I may be using it wrong. Im a bit new to using generics so I may have the code wrong — adviner
– adviner, Commented Mar 7, 2013 at 5:35

Ry- · Accepted Answer · 2013-03-07 05:34:40Z

2

Er, you've noticed that it takes multiple arguments, and you're obviously passing it only one — bool. Change it to list.JSONKeyName<bool, int, string, string>, as per the context.

answered Mar 7, 2013 at 5:34

Ry-♦

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1 Comment

adviner Over a year ago

OK i get it now. Thanks all for the help

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