haXe Forum > Check a Dynamic's type or castabil

• Nick Sabalausky Feb 24 at 02:13

  I'm a bit confused by the documentation relating to RTTI. Is there a way to check if a Dynamic variable contains a value of type X (*or* a type that inherits X)? For instance:

  class Base {}
  class Derived extends Base {}
  void Foo(x:Dynamic):Void
  {
      if( /* x is a String */ )
          trace("A");
      else if( /* x is a Base (or anything inherited from Base) */ )
          trace("B");
      else  // Something else
          trace("C");
  }
  
  Foo("hello"); // A
  Foo(new Base()); // B
  Foo(new Derived()); // B
  Foo(new Object()); // C
  Foo(7); // C

  If there's a way to do that without trying to cast(,) it and catching 'bad cast' exceptions: How? If not, how can I make a utility function like this work?:

  // Psuedo-code:
  public static function isCastableTo(var, type):Bool
  {
      try
      {
          var tmp = cast(var, type);
      }
      catch(e:Dynamic)
      {
          return false;
      }
      return true;
  }

  
  
• Philipp Klose Feb 24 at 20:56

  There you get all interfaces and the superclass for a class using RTTI Classdef. This works only if the classes are compiled with RTTI (Runtime Type Informations).
  For all other cases take a look at Type, there is a getClassName function, but this gives you no informations about the superclasses.
  For the most basic types you could work with Std.is().

• Nick Sabalausky Feb 26 at 00:29

  Thanks. Std.is() is exactly what I was looking for. I guess I overlooked it cause I was looking in Type and Reflect.

• Reply