Object construction with macro

GenNew.hx

import haxe.macro.Expr;
import haxe.macro.Context;

class GenNew
{
    macro public static function build () : Array<Field>
    {
        var fields = Context.getBuildFields();
        var args = [];
        var assigns = [];

        for (field in fields)
        {
            for (meta in field.meta)
            {
                if (meta.name == ":param")
                {
                    switch (field.kind)
                    {
                        case FVar(t, e), FProp(_, _, t, e):							
                            args.push({
                                name: field.name,
                                type: t,
                                opt: false
                            });
							
                            var name = field.name;
                            assigns.push(macro this.$name = $i{name});

                        default:
                    }
                }
            }
        }

        var f = {
            kind: FFun({
                args: args,
                expr: {
                    expr: EBlock(assigns),
                    pos: Context.currentPos()
                },
                params: [],
                ret: null
            }),
            name: "new",
            pos: Context.currentPos(),
            access: [APublic]
        };
		
        fields.push(f);
		
        return fields;
    }
}

Test.hx

@:build(GenNew.build())
class Test
{
    @:param public var i(default, null):Int;
    @:param private var s:String;
	
    public function show ()
    {
        trace(i, s);
    }

    public static function main ()
    {
        var obj = new Test(19, "hello macro");
        obj.show();
    }
}