The Strategy Pattern

The Strategy Pattern is a behavioral software design pattern.

It enables selecting an algorithm at runtime instead of hardcoding only one possible solution.

We’ll take a look at what it actually is and how it can help you to write better software.

The issue

Whenever you hard-code some very specific logic, without the ability to replace it on-demand, you’re tying yourself to that specific logic.

No way to replace it, except changing code. And sometimes changing code is not what you want to do, at all.

An object-oriented example

Imagine a class which is responsible to handle the creation of reports. In this particular case, you want to send reports out and have hard-coded an algorithm to send them over to a printer.

class ReportService {
  createReportAndSend() {
    // ...
    // ...
    const result = sendReport(report);
    if (result.error != null) {
      throw new Error("Sending report failed");
    }
  }
  sendReport(report: Report): ReportSendResult {
    const printerAddress = getPrinterAddress();
    const serializedReport = serializeReport(report);
    return sendReportToPrinter(serializedReport);
  }
}