Switch case on type c

Question

Possible Duplicate    C  - Is there a better alternative than this to   39 switch on type  39         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

User · Answer

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); }
}

User · Answer

Yes  you can switch on the name     switch  obj GetType   Name        case  TextBox

User · Answer

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 lt WebControl gt  x   gt       WebControl code here            this Case lt TextBox gt  x   gt       TextBox code here            this Case lt ComboBox gt  x   gt       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 lt object gt  Switch params Func lt object  Action gt    tests        return o   gt                var  case   tests              Select f   gt  f o                FirstOrDefault a   gt  a    null            if   case    null                         case                        private Func lt object  Action gt  Case lt T gt  Action lt T gt  action        return o   gt  o is T    Action       gt  action  T o      Action null      Almost brings tears to your eyes  right   Nonetheless  it works  Enjoy

User · Answer

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

User · Answer

Update C  7  Yes  Source  switch shape        case Circle c          WriteLine   circle with radius  c Radius             break      case Rectangle s when  s Length    s Height           WriteLine    s Length  x  s Height  square            break      case Rectangle r          WriteLine    r Length  x  r Height  rectangle            break      default          WriteLine   lt unknown shape gt             break      case null          throw new ArgumentNullException nameof shape        Prior to C  7  No    http   blogs msdn com b peterhal archive 2005 07 05 435760 aspx     We get a lot of requests for addditions to the C  language and today   I m going to talk about one of the more common ones - switch on type    Switch on type looks like a pretty useful and straightforward feature    Add a switch-like construct which switches on the type of the   expression  rather than the value  This might look something like   this    switch typeof e             case int         break           case string      break           case double      break           default          break          This kind of statement would be extremely useful for adding virtual   method like dispatch over a disjoint type hierarchy  or over a type   hierarchy containing types that you don t own  Seeing an example like   this  you could easily conclude that the feature would be   straightforward and useful  It might even get you thinking  Why don t   those    amp    lazy C  language designers just make my life easier and   add this simple   timesaving language feature        Unfortunately  like many  simple  language features  type switch is   not as simple as it first appears  The troubles start when you look at   a more significant  and no less important  example like this    class C    interface I    class D   C  I     switch typeof e    case C      break  case I      break  default      break      Link  https   blogs msdn microsoft com peterhal 2005 07 05 many-questions-switch-on-type

[c#] Switch case on type c#

Examples related to c#

Examples related to .net

Examples related to optimization

Examples related to switch-statement