ezura

import Foundation

func f() {
    unowned var unownedValue: NSDate?
    unownedValue = NSDate()
}

ezura

void main() {
  var tmp = "tmp";
  final finalVar = tmp;
  // Const variables must be initialized with a constant value.
//   const constVar = tmp;
  const _constVar = "const";
  const constVar = _constVar;
  print(finalVar + constVar);
}

ezura

void main() {
  for (int i = 0; i < 5; i++) {
    print('hello ${i + 1}');
  }
  
  for (var i in ["1", false]) {
    print(convertToBool(i));
  }
}

ezura

v1 + v2 + v3
// evaluation order: v1 v2 v3

v1 + v2 * v3
// evaluation order: v1 v2 v3

v1 + v2 * (v3 + v4) + v5
// evaluation order: v1 v2 v3 v4 v5

ezura

enum N {
    case never(Never)
}

func f(_ v: N) {
    switch v {
    case .never(let naver):
        print(naver)
    }
}

ezura

var v: Int?
if (a?.v = 1) == nil {
    // if a is nil, do something
}

ezura

var global: Any? = nil

class A {
    deinit {
        global = self
    }
}

do {
    _ = A()

ezura

/*
 event | without didSet | have didSet
 start 0 0
 0 0
 set 1 1
 1 0
 1 0
 1 0
 end 1 1
 --- 1

ezura

int v = 0;

// 意図しているコード
if(v == 0) { ... } // `if(1)` と評価

// `==` と `=` を書き間違えたコード
if(v = 0) { ... } // `if(0)` と評価

ezura

Typed error can be useful in certain cases, especially when accompanied with NoError type.

For example, in reactive programming, https://github.com/ReactiveCocoa/ReactiveSwift (typed error) allows us to create UI bindings only if Error is NoError, i.e.:

static func <~ <Source: BindingSource> (provider: Self, source: Source) -> Disposable? 
    where Source.Value == Value, Source.Error == NoError { ... }
    
// example
let alphaSignal: Signal = ...