Haxe Forum > Templates like C++ / Java ?

• raul Aug 01 at 16:42

  Is it possible to write code like:

  class BaseClass {
      ...
  }
  
  class AClass {
      ...
      public <T extends BaseClass> T functionName(Class<T> type) {
          return type.cast(systems.get(type));
      }
      ...
  }

  I did not found a way looking on documentation. Thanks.

• Justin L Mills Aug 02 at 02:14

  Not sure what you mean exactly but the syntax is far from haxe.

  Stuff like...
  

  public function fred<T>( t: T ){ }

  is possible but generics are complex to get right especially if you trying to only use them in a method, probably easier to consider Macros.

• raul Aug 02 at 08:55

  Syntax is for Java.

  I just want to ensure that compiler allows this:
  

  class Derived extends BaseClass{
      public function on_derived() : Void {
          trace('Go');
      }
  }
  
  ...
  AClassInstance = new AClass();
  ...
  AClassInstance.functionName(Derived).on_derived(); // Derived extends BaseClass, so Ok
  ...

  
  But also should forbid this:
  

  class Derived2 extends OtherClassNotDerivedFromBaseClass {
      public function other_function () : Void {
          trace('Other trace');
      }
  }
  ...
  AClassInstance.functionName(Derived2).other_function(); // This should throw a compiler error, Derived2 does not extends BaseClass
  ...

  Any way to achieve this?

• Justin L Mills Aug 03 at 21:20

  AClassInstance.functionName(Derived)

  
  Sorry this is not valid haXe syntax and makes no sense to me.
• jan Aug 04 at 00:04

  Raul,

  This forum is for simple beginners questions.
  It's best to ask your question on the mailing list, where all the people are, and where you will get a proper answer.
  https://groups.google.com/forum/?hl=en#!forum/haxelang

  Cheers,

  Jan

  PS: That is valid syntax btw.

• Liburn Aug 13 at 22:13

  This is working for Haxe 2.10 prior latest SVN changes:

  class BaseClass {
      public function on_derived() : Void {
          trace('Base');
      }
  }
  class Derived extends BaseClass {
      public override function on_derived() : Void {
          trace('Derived');
      }
  }
  
  class AClass {
      public function new() {
      }
       public function functionName<T:BaseClass>(type:Class<T>):T {
          return std.Type.createEmptyInstance(type);
      }
       public function static_functionName<T:BaseClass>(type):T {
          return type;
      }
  }
  
  class Derived2 extends AClass {
      public function other_function () : Void {
          trace('Other trace');
      }
  }

  var AClassInstance = new AClass();
  AClassInstance.functionName(Derived).on_derived(); // OK
  AClassInstance.functionName(Derived2).other_function(); // compiler ERROR
  

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