Hands-On Design Patterns with C# and .NET Core

Open/closed principle (OCP)

The open/closed principle, the O in SOLID, is represented by the different InventoryCommand classes. Instead of having an implementation of the InventoryCommand class per command, the team could have defined a single class containing multiple if statements. Each if statement would determine what functionality to execute. For example, the following illustrates how the team could have broken this principle:

internal bool InternalCommand(string command){    switch (command)    {        case "?":        case "help":            return RunHelpCommand();         case "a":        case "addinventory":            return RunAddInventoryCommand();         case "q":        case "quit":            return RunQuitCommand();        case "u":        case "updatequantity":            return RunUpdateInventoryCommand();        case "g": case ...