Simple initilizators in method parameters

Question

I built a fluent interface like this:

criador.Include("Idade", 21).Include("Idade", 21);

Can I do something like this:

criador.Include({"Idade", 21},{"Idade", 21});

I tryed to user method with params keyword:

public myType Include(params[] KeyValuePair<string,object> objs){
    //Some code
}

But I need to do this:

criador.Include(new KeyValuePair<string, object>{"Idade", 21}, new KeyValuePair<string, object>{"Idade", 21});

The point is that i dont want to write no "new" keyword on the methods

Answer 1

You could use an implicit conversion:

public class ConvertibleKeyValuePair
{
    public ConvertibleKeyValuePair(string key, int value)
    {
        _key = key;
        _value = value;
    }

    public static implicit operator ConvertibleKeyValuePair(string s)
    {
        string[] parts = s.Split(';');
        if (parts.Length != 2) {
            throw new ArgumentException("ConvertibleKeyValuePair can only convert string of the form \"key;value\".");
        }
        int value;
        if (!Int32.TryParse(parts[1], out value)) {
            throw new ArgumentException("ConvertibleKeyValuePair can only convert string of the form \"key;value\" where value represents an int.");
        }
        return new ConvertibleKeyValuePair(parts[0], value);
    }

    private string _key;
    public string Key { get { return _key; } }

    private int _value;
    public int Value { get { return _value; } }

}

// Tests

private static ConvertibleKeyValuePair[] IncludeTest(
    params ConvertibleKeyValuePair[] items)
{
    return items;
}

private static void TestImplicitConversion()
{
    foreach (var item in IncludeTest("adam;1", "eva;2")) {
        Console.WriteLine("key = {0}, value = {1}", item.Key, item.Value);
    }
    Console.ReadKey();
}

Answer 2

One way would be to use Tuples:

criador.Include(Tuple.Create("Idade", 21), Tuple.Create("Idade", 21));

Or you could create a type that can hold the values:

criador.Include(new StrIntDict{ {"Idade", 21}, {"Idade", 21} });

Where StrIntDict is basically Dictionary<string, int>: it has to implement IEnumerable and have a method Add(string, int). (You could use Dictionary<string, int> directly, but I think your goal is brevity, which such a long name doesn't help much.)

Answer 3

Another way is to write several overloads: one overload for each additional couple of parameters required. It may seems an overkill but actually can make code quite clear.

public void Include(string k0, object v0) { ... }
public void Include(string k0, object v0, string k1, object v1) { ... }
public void Include(string k0, object v0, string k1, object v1, string k2, object v2) { ... }
public void Include(string k0, object v0, string k1, object v1, string k2, object v2, string k3, object v3) { ... }
public void Include(string k0, object v0, string k1, object v1, string k2, object v2, string k3, object v3, string k4, object v4) { ... }

Each method does a different operation. The bad thing, you have a fixed number of maximum numbers of parameters.

Good thing, you can optimize the call for each function increasing performance.

You can also use this technique using extensions methods for a base class or an interface if needed.