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Hoo

Haxe Operator Overloading (Hoo), is a library that enables operator overloading for Haxe.

Hoo has built-in overloaded operators for haxe.Int64. Here's an example:

var i64 = Int64.ofInt(123456789);

// Output: 12345678900000123
trace(i64 * 100000000 + 123);

Installation

I have uploaded Hoo to haxelib. To install it, run this in the shell:

haxelib install hoo

Now you can use Hoo in your code.

You can compile to JavaScript:

haxe -lib hoo -main Your.hx -js your-output.js

, or SWF:

haxe -lib hoo -main Your.hx -swf your-output.swf

, or any other platform that Haxe supports.

Note that Hoo requires Haxe 2.10.

Usage

In the following example, we'll overload the concatenation operator for Arrays.

Step 1: Enable operator overloading

Create Sample.hx with the following content:

@:build(com.dongxiguo.hoo.OperatorOverloading.enableByMeta(":hoo"))
class Sample
{
  @:hoo public static function main()
  {
    var stringArray = ["H", "el", "lo, "] + [ "Wo", "rld!" ];
    trace(stringArray.join(""));
  }
}

To enable operator overloading, you must add @:build(com.dongxiguo.hoo.OperatorOverloading.enableByMeta(":hoo")) for classes that use overloaded operators, and add @:hoo for methods that use overloaded operators.

The operator + will be replaced to a function call to evaluate. If you compile Sample.hx, Haxe will complain that it cannot find the field evaluate.

Step 2: Implement the overloading function

Create ArrayConcatenationEvaluator.hx with the following content:

import com.dongxiguo.hoo.selector.BinaryOperatorSelector;
import com.dongxiguo.hoo.selector.binopTag.AddTag;
class ArrayConcatenationEvaluator
{
  public static function evaluate<T>(
    selector: BinaryOperatorSelector<AddTag, Array<T>, Array<T>>,
    left:Array<T>, right:Array<T>):Array<T>
  {
    return left.concat(right);
  }
}

Step 3: Use ArrayConcatenationEvaluator

Add using ArrayConcatenationEvaluator; to your Sample.hx:

using ArrayConcatenationEvaluator;
@:build(com.dongxiguo.hoo.OperatorOverloading.enableByMeta(":hoo"))
class Sample
{
  @:hoo public static function main()
  {
    // stringArray is ["H", "el", "lo, ", "wo", "rld!" ];
    var stringArray = ["H", "el", "lo, "] + ["wo", "rld!"];
    trace(stringArray.join(""));
  }
}

Step 4: Run it!

haxe -x Sample.hx

Now you will see it outputs Hello, world!.

Built-in overloads

There are built-in overloaded operators for haxe.Int64 and native types. To enable them, type using com.dongxiguo.hoo.Int64Evaluators; and/or using com.dongxiguo.hoo.NativeEvaluators;:

#if (haxe_211 || haxe3)
using com.dongxiguo.hoo.NativeEvaluators;
using com.dongxiguo.hoo.Int64Evaluators;
#else
using com.dongxiguo.hoo.Int64Evaluators;
using com.dongxiguo.hoo.NativeEvaluators;
#end
@:build(com.dongxiguo.hoo.OperatorOverloading.enableByMeta(":hoo"))
class Sample
{
  @:hoo public static function main()
  {
    var i64 = Int64.ofInt(123456789);

    // Output: 12345678900000123
    trace(i64 * 100000000 + 123);
  }
}

If you want to overload == for haxe.Int64, you must:

  • Put using Int64Evaluators; before using NativeEvaluators; for Haxe 2.10;
  • Put using NativeEvaluators; before using Int64Evaluators; for Haxe 2.11.

License

See https://github.com/Atry/hoo/blob/master/LICENSE