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
behavioralIteratorView pattern
structuralProxyView pattern
creationalSingletonView pattern
Basics
Categorybehavioralstructuralcreational
Summary———
IntentProvide a way to access elements of an aggregate sequentially while hiding the underlying representation.Provide a surrogate or placeholder for another object to control access to it.Ensure a class has only one instance and provide a global access point to it.
Decision factors
ProblemA collection needs to be traversed without exposing how it is stored internally.A client needs to interact with an object indirectly because the real object may be expensive, sensitive, or remote.A system needs exactly one shared instance of a class, and that instance must be globally accessible without allowing uncontrolled duplication.
Tradeoffs
  • Can add extra classes and abstraction for simple collections
  • May be unnecessary when built-in language iteration is already enough
  • Adds another layer of indirection
  • Can make the design more complex when the extra control is unnecessary
  • Can make dependencies harder to test if the singleton is used everywhere
  • May introduce hidden global state that complicates debugging and concurrency
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
  • Mobile
  • UI kits
  • Cross-platform systems
  • Web
  • Backend
  • Mobile
  • UI kits
  • Cross-platform systems
Integration notesIterator is useful for pagination, custom collections, ordered traversal, and any case where clients should not know the internal data structure.Proxy is useful for lazy loading, access control, caching, logging, and remote service wrappers.Singleton is useful for centralized services like configuration, logging, caching, and shared application state.