Analysis

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

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Abstract FactoryAdapterBridgeBuilderChain of ResponsibilityCommandCompositeDecoratorFacadeFactory MethodFlyweightInterpreterIteratorMediatorMementoObserverPrototypeProxySingletonStateStrategyTemplate MethodVisitor

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Analysis

Pattern comparison

Reviewing 3 patterns.

Criteria
structuralDecoratorView pattern
structuralFlyweightView pattern
behavioralObserverView pattern
Basics
Categorystructuralstructuralbehavioral
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.Use sharing to support large numbers of fine-grained objects efficiently by separating shared intrinsic state from per-object extrinsic state.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.A system creates a large number of similar objects, but storing all of their state separately uses too much memory.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.
  • Adds complexity because state must be split into shared and unshared parts
  • Can be harder to understand when many objects depend on an external context
  • 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.Flyweight is useful when thousands or millions of similar objects need to be represented efficiently, such as trees, glyphs, tiles, or UI tokens.Observers work well inside a single application boundary for UI events, domain events, and in-process notifications where subscribers change dynamically.