I'll Be Backend
Search lessons / @illbebackend
Principles

Abstraction: Hide the Data Structure

Abstraction means callers use what an object does and never see how it stores its data, so the storage can change without them. These lessons take a warehouse whose stock map is read and changed by three classes, move each use into the warehouse as receive, pick and quantity, and make the map private, so keeping stock per delivery becomes a change inside one class.

Pick your language

Abstraction: hide the data structure in Java, step 2: Oldest delivery firstJava · ~4 minAbstraction in JavaAbstraction: hide the data structure in Kotlin, step 2: Oldest delivery firstKotlin · ~4 minAbstraction in KotlinAbstraction: hide the data structure in C#, step 2: Oldest delivery firstC# · ~4 minAbstraction in C#Abstraction: hide the data structure in C++, step 2: Oldest delivery firstC++ · ~4 minAbstraction in C++Abstraction: hide the data structure in Python, step 2: Oldest delivery firstPython · ~4 minAbstraction in PythonAbstraction: hide the data structure in Ruby, step 2: Oldest delivery firstRuby · ~4 minAbstraction in RubyAbstraction: hide the data structure in PHP, step 2: Oldest delivery firstPHP · ~4 minAbstraction in PHPAbstraction: hide the data structure in TypeScript, step 2: Oldest delivery firstTypeScript · ~4 minAbstraction in TypeScriptAbstraction: hide the data structure in Go, step 2: Oldest delivery firstGo · ~4 minAbstraction in GoAbstraction: hide the data structure in Rust, step 2: Oldest delivery firstRust · ~5 minAbstraction in RustAbstraction: hide the data structure in Swift, step 2: Oldest delivery firstSwift · ~5 minAbstraction in Swift

When to use it

Use it when

Several classes read or change one collection, and the way it is stored may change.

Skip it when

One short function owns the map and nothing outside it reads it. Methods around it add lines and hide nothing.

Spot it by

get, put or merge called on another object's collection, or the same lookup copied into several classes.