stepdad/src/decorators/Param.ts

Stupid simple and lightweight dependency injection

export const Param: any = (desc: string) => {
  return (target: any, name: "execute", index: number) => {
    let constructor = target.constructor;

    let definitions: any[] = (constructor.paramDefinitions = []);

    let type = Reflect.getMetadata("design:paramtypes", target, name);
    let name_fn = target[name] && getFunctionParameterName(target[name], index);

    console.log("desc: ", desc);
    console.log("type: ", type);
    //console.log("name: ", getFunctionParameterName(target[name], index));
    console.log("definitions: ", definitions);

    definitions[index] = {
      type,
      index,
      name,
      name_fn,
    };
  };
};

export function parseFunctionParameterNames(
  fn: Function
): string[] | undefined {
  let groups = fn.toString().match(/^[^{=]*\(([\w\d$-,\s]*)\)/);

  return groups ? groups[1].trim().split(/\s*,\s*/) : undefined;
}

const getFunctionParameterName = (fn: Function, index: number): string => {
  let paramNames: string[] | undefined;

  if ((fn as any).__paramNames) {
    paramNames = (fn as any).__paramNames;
  } else {
    paramNames = (fn as any).__paramNames = parseFunctionParameterNames(fn);
  }

  return (paramNames && paramNames[index]) || `param${index}`;
};