I have extended the Label class as follows:
public class MyLabel: Label {
public Button btn;
public string mydata;
}
In my main program, I instantiated a new instance:
MyLabel lbl = new MyLabel();
lbl.mydata = "some data here";
lbl.btn = new Button();
lbl.btn.Click += new EventHandler(button_pressed);
this.Controls.Add(lbl); // Adds the label to the form
this.Controls.Add(lbl.btn); // Adds the button to the form
And I created a method to handle the button click event:
void button_pressed(Object sender, EventArgs e) {
Button btn = (Button)sender;
//Now I have an access to the property within MyLabel instance.
// but how can I access the parent object?
// I need to access the sibling property [mydata] string from here
btn.Siblings["mydata"] = "some other thing" ; //Something like this
MyLabel lbl = btn.ParentObject(); //Or something like this
lbl.mydata = "Some other thing";
}
This looks like WinForms, in which case either a UserControl or extending Button class might be a good way to go - just maintain a reference to the parent (a bit more complicated with UserControl, you'd need to define the click event on that control, otherwise you're back to "square 1") I like the Tag property solution as well, although there is an additional cast, and no guarantee of type safety (since Tag is an object, it can be anything by the time you try to access it).
However, let's say you're looking for a more general solution; let's also say that the class in question is sealed, has no Tag or similar purpose property, and a Controls collection is not available (or looping through it is not desirable for performance reasons). To my best knowledge, you can't determine parent object; but you can easily provide your own "Controls" style dictionary, mapping the Button to the parent:
public class MyLabel: Label {
public static Dictionary<Button, MyLabel> ParentMap = new Dictionary<Button, MyLabel>();
public Button btn;
public string mydata;
public void AddToParentMap() => ParentMap[btn] = this;
}
When you're creating an instance of MyLabel, just call the AddToParentMap() function (can't be done in constructor, because this pointer is not available until the object is created):
MyLabel lbl = new MyLabel();
lbl.AddToParentMap();
You can then just look it up, fast and easy, in your click event:
void button_pressed(Object sender, EventArgs e) {
Button btn = (Button)sender;
var label = MyLabel.ParentMap[btn];
//...
//Your code...
}
Unlike the Tag solution, type safety is guaranteed - you always know you're accessing a MyLabel object.
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