[c#] Switch case on type c#

Possible Duplicate:
C# - Is there a better alternative than this to 'switch on type'?

Hello suppose i get a big if/else on class type. it's there a way to do it with a switch case ?

Example :

function test(object obj)
{
if(obj is WebControl)
{

}else if(obj is TextBox)
{

}
else if(obj is ComboBox)
{

}

etc ...

I would like to create something like

switch(obj)
{
case is TextBox:
break;
case is ComboBox:
break;

}

}

The following code works more or less as one would expect a type-switch that only looks at the actual type (e.g. what is returned by GetType()).

public static void TestTypeSwitch()
{
    var ts = new TypeSwitch()
        .Case((int x) => Console.WriteLine("int"))
        .Case((bool x) => Console.WriteLine("bool"))
        .Case((string x) => Console.WriteLine("string"));

    ts.Switch(42);     
    ts.Switch(false);  
    ts.Switch("hello"); 
}

Here is the machinery required to make it work.

public class TypeSwitch
{
    Dictionary<Type, Action<object>> matches = new Dictionary<Type, Action<object>>();
    public TypeSwitch Case<T>(Action<T> action) { matches.Add(typeof(T), (x) => action((T)x)); return this; } 
    public void Switch(object x) { matches[x.GetType()](x); }
}

Here's an option that stays as true I could make it to the OP's requirement to be able to switch on type. If you squint hard enough it almost looks like a real switch statement.

The calling code looks like this:

var @switch = this.Switch(new []
{
    this.Case<WebControl>(x => { /* WebControl code here */ }),
    this.Case<TextBox>(x => { /* TextBox code here */ }),
    this.Case<ComboBox>(x => { /* ComboBox code here */ }),
});

@switch(obj);

The x in each lambda above is strongly-typed. No casting required.

And to make this magic work you need these two methods:

private Action<object> Switch(params Func<object, Action>[] tests)
{
    return o =>
    {
        var @case = tests
            .Select(f => f(o))
            .FirstOrDefault(a => a != null);

        if (@case != null)
        {
            @case();
        }
    };
}

private Func<object, Action> Case<T>(Action<T> action)
{
    return o => o is T ? (Action)(() => action((T)o)) : (Action)null;
}

Almost brings tears to your eyes, right?

Nonetheless, it works. Enjoy.

Yes, you can switch on the name...

switch (obj.GetType().Name)
{
    case "TextBox":...
}

The simplest thing to do could be to use dynamics, i.e. you define the simple methods like in Yuval Peled answer:

void Test(WebControl c)
{
...
}

void Test(ComboBox c)
{
...
}

Then you cannot call directly Test(obj), because overload resolution is done at compile time. You have to assign your object to a dynamic and then call the Test method:

dynamic dynObj = obj;
Test(dynObj);