Skip to content

Latest commit

 

History

History
85 lines (59 loc) · 2.7 KB

readme.md

File metadata and controls

85 lines (59 loc) · 2.7 KB
Raw

S.Leschev Design Patterns (Swift 5+)

Google Engineering Level: L6+

🏆 Awards

Ranking #Dev: Global TOP 300 (Certificate)

Sergey Leschev

Languages: Swift, Shell, Database (T-SQL, PL/SQL, MySQL), Concurrency (Python3).

Algorithms: linked lists, binary search, hash table, queue/stack, dfs/bfs, sort, heap/hash, two pointers, sliding window, tree, greedy problems etc.

👓 Observer

The observer pattern is used to allow an object to publish changes to its state. Other objects subscribe to be immediately notified of any changes.

Example

protocol PropertyObserver : class {
    func willChange(propertyName: String, newPropertyValue: Any?)
    func didChange(propertyName: String, oldPropertyValue: Any?)
}

final class TestChambers {

    weak var observer:PropertyObserver?

    private let testChamberNumberName = "testChamberNumber"

    var testChamberNumber: Int = 0 {
        willSet(newValue) {
            observer?.willChange(propertyName: testChamberNumberName, newPropertyValue: newValue)
        }
        didSet {
            observer?.didChange(propertyName: testChamberNumberName, oldPropertyValue: oldValue)
        }
    }
}

final class Observer : PropertyObserver {
    func willChange(propertyName: String, newPropertyValue: Any?) {
        if newPropertyValue as? Int == 1 {
            print("Okay. Look. We both said a lot of things that you're going to regret.")
        }
    }

    func didChange(propertyName: String, oldPropertyValue: Any?) {
        if oldPropertyValue as? Int == 0 {
            print("Sorry about the mess. I've really let the place go since you killed me.")
        }
    }
}

Usage

var observerInstance = Observer()
var testChambers = TestChambers()
testChambers.observer = observerInstance
testChambers.testChamberNumber += 1

Contacts

I have a clear focus on time-to-market and don't prioritize technical debt.

🛩️ #startups #management #cto #swift #typescript #database

📧 Email: [email protected]

👋 LinkedIn: https://linkedin.com/in/sergeyleschev

👋 Twitter: https://twitter.com/sergeyleschev

👋 Github: https://github.com/sergeyleschev

🌎 Website: https://sergeyleschev.github.io

🖨️ PDF: Download

ALT: SIARHEI LIASHCHOU