generics.md

Generics

Generics provide a technique for writing routines where the exact type of an object used is not known until runtime. Generics are a way of writing code that will deal with any type of a object but still maintain the object type integrity.

Generic Syntax

class CombineInator<T> {
  combineArray(inputArray : Array<T>) : string {
    let result = '';

    for (let i = 0; i < inputArray.length; i++) {
      if (i > 0) result += ',';
      result += inputArray[i].toString();
    }
    return result;
  }
}

The <T> syntax is used to indicate a generic type, and the name used for this generic type is T. The combineArray function also uses the generic type, meaning that inputArray must be an array of the type that was used to construct an instance of this class.

Creating generic class instances

let stringCombine = new CombineInator<string>();
let numberCombine = new CombineInator<number>();

When creating a new instance, we can substitute T with types, classes, or interfaces.