Analysis

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Analysis

Pattern comparison

Reviewing 3 patterns.

Criteria
creationalFactory MethodView pattern
behavioralMediatorView pattern
behavioralObserverView pattern
Basics
Categorycreationalbehavioralbehavioral
Summary———
IntentDefine a creation method behind a common interface so specialized creators can decide which concrete product to instantiate without changing the surrounding workflow.Define an object that encapsulates communication between a set of objects, keeping them from referring to each other directly.Define a subscription mechanism so multiple observers can react to subject events without the subject knowing concrete subscriber details.
Decision factors
ProblemA workflow needs to create one of several related concrete objects, but constructing them directly in client code spreads creation logic and tightly couples the caller to specific implementations.Multiple objects need to coordinate behavior, but direct references between them create tight coupling and complex dependencies.A system needs to notify multiple dependent objects when state changes occur, but hardcoding those dependencies makes the design rigid and tightly coupled.
Tradeoffs
  • Adds extra indirection and more types compared with direct construction
  • Can feel unnecessarily abstract when object creation is simple and unlikely to vary
  • The mediator can become large and complex if it takes on too much coordination logic.
  • Centralizing behavior can make the mediator a single point of failure if it is poorly designed.
  • Notification flows can become hard to trace when many observers react to the same event
  • Observers may receive updates they do not need unless subscriptions are carefully designed
Practical fit
Languages
  • typescript
  • java
  • python
  • angular
  • react
  • react-native
  • csharp
  • dotnet
  • typescript
  • java
  • python
  • angular
  • react
  • react-native
  • csharp
  • dotnet
  • typescript
  • java
  • python
  • angular
  • react
  • react-native
  • csharp
  • dotnet
Platforms
  • Applications
  • APIs
  • Frameworks
  • Service layers
  • Web
  • Backend
  • Mobile
  • UI kits
  • Cross-platform systems
  • Web
  • Backend
  • Event-driven systems
Integration notesFactory Method is useful when framework hooks, integrations, or environment-specific workflows need to create interchangeable implementations behind a stable contract.Mediator is useful for chat systems, form coordination, workflow orchestration, and any domain where many components must collaborate without knowing about each other.Observers work well inside a single application boundary for UI events, domain events, and in-process notifications where subscribers change dynamically.