Analysis

Compare patterns

Evaluate design patterns side by side across intent, tradeoffs, languages, and integration fit.

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Analysis

Pattern comparison

Reviewing 3 patterns.

Criteria
structuralDecoratorView pattern
behavioralMediatorView pattern
behavioralObserverView pattern
Basics
Categorystructuralbehavioralbehavioral
SummaryWrap an object with other objects that implement the same contract so responsibilities can be layered dynamically.——
IntentWrap an object with other objects that implement the same contract so responsibilities can be layered dynamically.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 system needs to add optional behaviors to an object without creating many subclasses for every feature combination.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
  • Can introduce many small wrapper classes that are harder to trace in debugging.
  • Ordering of decorators matters, so composition needs to be deliberate.
  • Keeps responsibilities modular and easy to combine.
  • 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
  • frontend
  • backend
  • services
  • Web
  • Backend
  • Mobile
  • UI kits
  • Cross-platform systems
  • Web
  • Backend
  • Event-driven systems
Integration notesDecorators work well for cross-cutting concerns such as logging, retry, caching, compression, and telemetry because each layer keeps the same interface while adding one concern.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.