Everyone likes beautiful design. I do, too. But, the use of design patterns is not just to make something look good. Everything we do should have a purpose.

The GoF classified object-oriented design patterns as creational, structural, and behavioral. For Julia, let's take a different perspective and classify our patterns by their respective software quality objectives as follows:

• Reusability
• Performance
• Maintenance
• Safety

Let's understand each of these in the following sections.