Factory Method
Factory Method separates object creation from the workflow that uses the object, allowing a subtype or configuration to choose the concrete product.
Visual logic for real ideas
Run the idea.
We do not compress a book into a summary. We take one useful idea, model it as a system, run an example, and show where it stops working.
strategy.sys
INPUTBehavior keeps changing
RULEIsolate what varies
RUNSwap one strategy
OUTPUTSystem stays stable
CAVEATDo not abstract one case
Launch collection 01
Design patterns,
made visible.
Ten reusable software ideas from one source book, rebuilt as original logic flows, practical examples, and explicit trade-offs.
Creational
Structural
Decorator
Decorator wraps an object with optional layers, allowing capabilities to be combined at runtime without creating a subclass for every combination.
Adapter
Adapter converts an existing interface into the interface a client expects, containing incompatibility at one explicit system boundary.
Facade
Facade offers a small task-oriented interface over a complicated subsystem, reducing the knowledge each caller needs for common workflows.
Behavioral
Strategy
When one task has several valid ways to run, Strategy keeps the workflow stable while the decision-making rule can change independently.
Observer
Observer turns a state change into a broadcast so multiple dependents can react without the source knowing their concrete implementations.
Command
Command packages a request as an object so actions can be queued, logged, retried, composed, or reversed independently from the caller.
Template Method
Template Method defines a stable algorithm sequence while allowing selected steps to vary through subclass hooks or overrides.
Iterator
Iterator provides a standard way to traverse a collection while hiding whether the underlying structure is an array, tree, stream, or remote page.