Security with character, or a few more words about the Singleton pattern

- How, and he is also a singleton? And I thought he was normal!

- How many times can I tell you that the words singleton, mediator, decorator and even prototype have nothing to do with the orientation of the code?

(conversation calling a smoker and calling a normal programmer)

Hello everyone, I'm Maxim Kravets , CEO of the Holyweb web engineering team, JavaScript adepts. And today I want to talk about design patterns.

Let's take a look at a small piece of code:

@Injectable()
export class SomeClass implements SomeInterface {
  private currentData: Data
 
 setData() {
      this.currentData = new Data()
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, : « decorator SomeClass Dependency Injection, setData Builder new currentData ...»

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public static getInstance(): SingletonClassName { 
    !instance ? instance = new SingletonClassName : instance
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

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//   
class DataBase {
//       Singleton-
private static instance

//   ,     
//       new
private constructor() {
  //       
  ….
  // ,    
  this.instance = null
}
//     
//  ,       Singleton-
public static getInstance() {
if ( this.instance === null ) {
//   ,  
 this.instance = new DataBase()
}

//   ,  
return this.instance
}
//     query  
//    
public getQuery(payload) {
	//    
	...
}
}

//   
class AppModule {
	//    
	Data() {		
		//   
		let foo = DataBase.getInstance()
		let bar = DataBase.getInstance()

		// foo    ,
		//   bar
		foo.getQuery("SELECT ...")
		bar.getQuery("SELECT ...")
}
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

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, , . , , : Telegram @maximkravec. 

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