當變量改變時得到通知

Question

有沒有辦法在變量發生變化時獲得？ 如果是這樣，我怎樣才能做到這一點？

Answer 1

“官方”的方法是INotifyPropertyChanged 。 例如，它被 UI 的（Windows 窗體、WPF）用來在控件綁定到的數據對象更新時自動刷新控件。

public class MyClass : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    ...
}

然后你可以實現這樣的屬性

private string _name;
public string Name
{
    get { return _name; }
    set {
        if (value != _name) {
            _name = value;
            OnPropertyChanged(nameof(Name));
        }
    }
}

你可以這樣使用它：

var myObj = new MyClass();
myObj.PropertyChanged += MyObj_PropertyChanged;

myObj.Name = "new name";

// Clean up (e.g. in a `Dispose()` method)
myObj.PropertyChanged -= MyObj_PropertyChanged;

假設這個事件處理程序：

// Will be called whenever a property of `MyClass` is updated.
private void MyObj_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    // Example
    if (e.PropertyName == nameof(MyClass.Name)) {
        var myObj = (MyClass)sender;
        //TODO: do something.
    }
}

Answer 2

只需檢查更新無效。 我認為這是在 Unity 中實現您想要的最簡單方法。

var varToCheckIfChanged; //This is the variable you want to know if it is still the same
var tempVar; //This variable stores the original value, and every time the varToCheckIfChanged changed, you update it.

//Gets called on Start of the scene
void Start
{
     tempVar = varToCheckIfChanged;
}

//Gets called every frame
void Update
{
    if(varToCheckIfChanged != tempVar)
    {
        Debug.Log("Variable changed!"); //Debug when the variable is updated
        var tempVar = varToCheckIfChanged;
    }

}