Abstract Factory

Abstract Factory creates families of related objects—UI widgets, cloud resources, database adapters—that must stay compatible within a theme or platform. Clients work with factory interfaces and product abstractions without knowing concrete vendors. Use it when switching entire stacks together matters more than swapping one class.

On interviews: explain the difference from Factory Method and Builder. A classic example is cross-platform UI kits or themed document exporters.

Common pitfalls: over-engineering when only one product varies; factories that become god-objects; leaking concrete product types through return signatures.

The trade-off is flexibility versus complexity—know when the simpler path is enough.

Checklist:

• Products in a family share compatibility constraints.
• Client code never names concrete vendors.
• Switching families is a configuration change.
• Keep family size small and cohesive.