dropecho.macros

A small Haxe library of compile-time build macros that generate constructors and fields onto a class at build time. Everything runs at compile time, so the library ships no runtime code of its own — only the code it generates.

Install

haxelib install dropecho.macros

Usage

Attach a macro to a class with @:build.

Constructor.fromFields

Generate a constructor from the class's variable fields. Each field becomes a constructor argument that is assigned to this.

@:build(dropecho.macros.Constructor.fromFields(true))
class Point {
	public var x:Int;
	public var y:Int;
}

new Point(1, 2); // x = 1, y = 2

Constructor.fromArgs

Fill in an empty constructor's body and create matching fields from its arguments.

@:build(dropecho.macros.Constructor.fromArgs(true))
class Point {
	public function new(x:Int, y:Int);
}

Constructor.fromTypeDef

Build a class (and a static build function) from a single configuration-object argument. The config's fields are copied onto the class and assigned in the constructor.

class Config {
	public var x:Int;
	public var y:Int;
}

@:build(dropecho.macros.Constructor.fromTypeDef(true))
class Point {
	public function new(config:Config);
}

The boolean argument on each macro controls whether the generated fields are public.

MakeOptional.OptionalType.optional

Copy another type's variable fields onto a class as public, optional (Null<T>) fields.

class Point {
	var x:Int;
	var y:Int;

	public function new() {}
}

@:build(dropecho.macros.MakeOptional.OptionalType.optional(Point))
class Config {
	public function new() {}
}

var c = new Config();
c.x = 1; // x and y copied from Point as Null<Int>

MathMacros.pow

Unroll an integer power into repeated multiplication at compile time (no runtime Math.pow). Compound arguments are bound to a temporary so they evaluate once.

import dropecho.macros.MathMacros;

MathMacros.pow(t, 3);     // => t * t * t
MathMacros.pow(1 - t, 2); // => { final b = 1 - t; b * b; }

Development

npm test   # run the utest suite (via dropecho.testing)

Tests are auto-discovered: any test/**/*Tests.hx class extending utest.Test is picked up by dropecho.testing — there is no hand-written test main.

License

MIT