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Decorators


Class Decorators​

Applied to class constructor for observing, modifying or replacing class definition

@controller("api")
class APIServer {
  constructor(private app:Express){

  }
}

// Receives the constructor of the class
declare type ClassDecorator = <TFunction extends Function>(target: TFunction) => TFunction | void;


// Implementation
function log(constructor: Function){
  console.log(`${constructor} Decroator Invoked`)
}

Method Decorators​

observing, modifying, or replacing method definition.


class APIServer {
  constructor(){

  }

  @log("Route added to API Server")
  public addRoute(path:string, action:Action){
    this._app.addRoute(path,action)
  }
}

Property Decorators​


Parameter Decorators​

Applied to method declaration for observing that a parameter has been defined

Decroator Appraoches

Decrator Function​

Must implement specific signatures based on use

Decrator Factory​

Enable you to receive parameters and construct the Decorators Need to have paranethsis in their definition.

Decorators are called at runtime with either approach.