Analysis

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Analysis

Pattern comparison

Reviewing 3 patterns.

Criteria
structuralFlyweightView pattern
behavioralObserverView pattern
creationalPrototypeView pattern
Basics
Categorystructuralbehavioralcreational
Summary———
IntentUse 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.Specify the kinds of objects to create using a prototypical instance, and create new objects by cloning that prototype.
Decision factors
ProblemA 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.Creating new objects from scratch can be expensive or repetitive when the system needs many similar variants.
Tradeoffs
  • 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
  • Can be difficult if the object graph contains deep references that need custom clone behavior
  • May require careful handling of mutable state to avoid shared-reference bugs
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
  • Web
  • Backend
  • Mobile
  • UI kits
  • Cross-platform systems
  • Web
  • Backend
  • Event-driven systems
  • Web
  • Backend
  • Mobile
  • UI kits
  • Cross-platform systems
Integration notesFlyweight 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.Prototype is useful when object creation is expensive, when many near-identical objects are needed, or when cloning preconfigured templates is simpler than rebuilding them.