I - Interface Segregation (ISP)

About

A class should not implement interfaces that it won't use.

Create interfaces based only on what the client needs, avoiding dependencies on things it won't use.

Usually impacts reduction of unecessary re-compilation.

Example

In this example, the Exec class, which is the class that uses the method, specifies what it wants from ClassA.

So now, Exec don't know ClassA anymore, it only knows Interface2. And if ClassA changes in the future, Exec won't need to be re-compiled (Since there is no more import A from '.../ClassA').

Main.ts

Registry.getInstance().provide('classA', new A());

Exec.ts

class Exec {
    @inject('classA')
    classA: Interface2;
}

export interface2 {
    method2(): void;
}

ClassA.ts

interface ARepo extends Interface1, Interface2 {
    method1(): void;
    method2(): void;
    method3(): void;
}

class A implements ARepo {
    method1(): void { ... }
    method2(): void { ... }
    method3(): void { ... }
}