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Sergey Leschev
Sergey Leschev

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πŸƒ Visitor Pattern

Visitor Pattern


The visitor pattern is used to separate a relatively complex set of structured data classes from the functionality that may be performed upon the data that they hold.

Github https://github.com/sergeyleschev/design-patterns

Example

protocol PlanetVisitor {
    func visit(planet: PlanetAlderaan)
    func visit(planet: PlanetCoruscant)
    func visit(planet: PlanetTatooine)
    func visit(planet: MoonJedha)
}

protocol Planet {
    func accept(visitor: PlanetVisitor)
}

final class MoonJedha: Planet {
    func accept(visitor: PlanetVisitor) { visitor.visit(planet: self) }
}

final class PlanetAlderaan: Planet {
    func accept(visitor: PlanetVisitor) { visitor.visit(planet: self) }
}

final class PlanetCoruscant: Planet {
    func accept(visitor: PlanetVisitor) { visitor.visit(planet: self) }
}

final class PlanetTatooine: Planet {
    func accept(visitor: PlanetVisitor) { visitor.visit(planet: self) }
}

final class NameVisitor: PlanetVisitor {
    var name = ""

    func visit(planet: PlanetAlderaan)  { name = "Alderaan" }
    func visit(planet: PlanetCoruscant) { name = "Coruscant" }
    func visit(planet: PlanetTatooine)  { name = "Tatooine" }
    func visit(planet: MoonJedha)       { name = "Jedha" }
}
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Usage

let planets: [Planet] = [PlanetAlderaan(), PlanetCoruscant(), PlanetTatooine(), MoonJedha()]

let names = planets.map { (planet: Planet) -> String in
    let visitor = NameVisitor()
    planet.accept(visitor: visitor)

    return visitor.name
}

names
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Sources: Github

Behavioral
In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication.
Source: wikipedia.org


🐝 Chain Of Responsibility
πŸ‘« Command Pattern
🎢 Interpreter Pattern
🍫 Iterator Pattern
πŸ’ Mediator Pattern
πŸ’Ύ Memento Pattern
πŸ‘“ Observer Pattern
πŸ‰ State Pattern
πŸ’‘ Strategy Pattern
πŸ“ Template Method
πŸƒ Visitor Pattern
🌰 Abstract Factory
πŸ‘· Builder Pattern
🏭 Factory Method
πŸ”‚ Monostate Pattern
πŸƒ Prototype Pattern
πŸ’ Singleton
πŸ”Œ Adapter Pattern
πŸŒ‰ Bridge Pattern
🌿 Composite Pattern
🍧 Decorator Pattern
🎁 Facade Pattern
πŸƒ Flyweight Pattern
β˜” Protection Proxy
🍬 Virtual Proxy


Contacts
I have a clear focus on time-to-market and don't prioritize technical debt. And I took part in the Pre-Sale/RFX activity as a System Architect, assessment efforts for Mobile (iOS-Swift, Android-Kotlin), Frontend (React-TypeScript) and Backend (NodeJS-.NET-PHP-Kafka-SQL-NoSQL). And I also formed the work of Pre-Sale as a CTO from Opportunity to Proposal via knowledge transfer to Successful Delivery.

πŸ›©οΈ #startups #management #cto #swift #typescript #database
πŸ“§ Email: sergey.leschev@gmail.com
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🌎 Medium: https://medium.com/@sergeyleschev
πŸ–¨οΈ PDF Design Patterns: Download

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