I'll Be Backend
Search lessons / @illbebackend
Principles

Coupling: Wrap a Third-Party Library

Coupling is how much one part of the code must change when another part changes. When business classes call a vendor's library directly, a vendor switch edits every one of them. These lessons take a car rental desk that charges cards through a payment library in two classes, move every call behind one wrapper class and an interface, and then switch vendors by adding one class.

Pick your language

Coupling: wrap a third-party library in Java, step 2: Finance moves to PayLaneJava · ~5 minCoupling in JavaCoupling: wrap a third-party library in C#, step 2: Finance moves to PayLaneC# · ~5 minCoupling in C#Coupling: wrap a third-party library in Python, step 2: Finance moves to PayLanePython · ~6 minCoupling in PythonCoupling: wrap a third-party library in PHP, step 2: Finance moves to PayLanePHP · ~6 minCoupling in PHPCoupling: wrap a third-party library in TypeScript, step 2: Finance moves to PayLaneTypeScript · ~5 minCoupling in TypeScript

When to use it

Use it when

A vendor library is called from more than one business class, or you may switch vendors.

Skip it when

The library is stable and everywhere, like the standard collections. A wrapper adds a class and hides nothing worth hiding.

Spot it by

Vendor class names, keys, units or status strings in more than one business class.