Question

I have a method that Inputs a text file from passed string, have to check whether the passed type’s TryParse is OK with read strings from stream, and then adds items to passed combobox

I tried to do this but stuck at how to pass the type and then check TryParse.

private void Input(string file, ComboBox cb, /* object passedType */)
        {
            if (File.Exists(c + "recent_IPs.txt"))
            {
                FileStream stream = new FileStream(c + "recent_IPs.txt", FileMode.Open);
                StreamReader reader = new StreamReader(stream);

                while (!reader.EndOfStream)
                {
                    string read = reader.ReadLine();
                    /* passedType t; */
                    if (/* passedType.TryParse(read, out t) */)
                    {
                        cb.Items.Add(read);
                    }
                }

                reader.Close();
                stream.Close();

                if (cb.Items.Count > 0)
                {
                    cb.SelectedIndex = 0;
                }
            }
        }

EDIT: By the way the “c” in

...
if (File.Exists(c + "recent_IPs.txt"))
...

is

string c = Directory.GetCurrentDirectory();

Answer 1

You’d have to do this with reflection:

• Change passedType to be of type Type
• Find the right method using Type.GetMethod or Type.GetMethods, noting that the method may be overloaded
• Call the method

Alternatively, if possible, change the method to accept a delegate:

private void Input(string file, ComboBox cb, Func<string, bool> validator)

then just call the delegate. You can then use:

Input(file, cb, text => { int dummy; return int.TryParse(text, out dummy); });

(etc)