Perform certain base class method calls only once instead of every instance of the class?

Question

I have a class that performs a login request on instantiation, I only want this login request to be performed by the base class and for all other instances to acknowledge that the login has been performed. Can anyone recommend how this can be achieved, would this be a use-case for making the login function static?

// Example
class Content {
    constructor() {
        this.performLogin()
    }

    performLogin() { // will making this static achieve my request?
        // go fetch if 1st time
        // else bypass this step
    }

    performLogout() {
        // perform log out once only
    }
}

class ContentOne extends Content {
    constructor() {
        super()
    }
    doSomethingElse() {
        //...
    }
}

class ContentTwo extends Content {
    constructor() {
        super()
    }
    alertUser() {
        //...
    }
}

const contentOne = new ContentOne()
const contentTwo = new ContentTwo()

https://stackoverflow.com/questions/35156270/static-constructor-in-javascript-es6 — Daniel A. White, Jan 05 '18 at 14:42

Daniel A. White · Answer 1 · 2018-01-05T15:31:18.827

2

A better design would be to have a LoginService that would manage that. If already logged in, it would just ignore the request. For example,

class LoginService {
   constructor() {
       this.isLoggedIn = false;
   }
   login() { 
       if (this.isLoggedIn) { return; } 
       // do work
       this.isLoggedIn = true;
   }
}

class Content {
    constructor(loginService) {
        this.loginService = loginService;
        this.performLogin()
    }

    performLogin() { 
        this.loginService.login();
    }

    performLogout() {
        // perform log out once only
    }
}

const loginService = new LoginService();
const contentOne = new ContentOne(loginService);
const contentTwo = new ContentTwo(loginService);

Making a function static won't prevent something being called more than once.

edited Jan 05 '18 at 15:31

answered Jan 05 '18 at 14:40

Daniel A. White

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Hey, have you an example of this? – styler Jan 05 '18 at 15:26
@styler added a super simple example – Daniel A. White Jan 05 '18 at 15:31
can a class talk directly to another class? What I mean is if I wanted to directly call functions in Content from LoginService like Content.someOtherFunction? – styler Jan 05 '18 at 16:26
@styler that would be a bad separation of concerns – Daniel A. White Jan 05 '18 at 16:29
What if the login class is private to only the content class? I don’t think I have the flexibility to add in a login class that I can instance and pass into each content instance is my problem – styler Jan 05 '18 at 16:38

Perform certain base class method calls only once instead of every instance of the class?

1 Answers1