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How to delete an object in Dart?

I want to basically delete the object I created. How to delete an object?

I checked the Object definition here , but couldn't find a way to do this. I am also curious if we can define destructors or not.

UPDATE The question is getting good answers. But I want to draw your attention to the case when I want to delete my objects or call a destructor. Let's say we want to create a pace using rectangles for this using the ports placed on it. Therefore, the idea is to have an object that has a link to the body of the rectangle and ports located at two ends. In fact, this object may require some other properties, such as [bool] selected or [bool] dragging or [List<RectElement>] connectedSquares . For example, when a user selects a rectangle and turns back, I want to make sure the rectangles are gone and my object is deleted. Therefore, this use case can provide a deeper understanding of the issue.

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You do not need to actively delete objects in Dart.

Dart is a garbage collected language, so any object you don’t reference will ultimately be garbage collected and freed by the runtime system.

So, all you have to do is clear any variables that you have, an object reference.

Garbage collection is really implied in the language specification. The specification does not say that garbage collection exists (it does not even mention the concept), but the language and libraries are designed in such a way that garbage collection is possible: objects that the program cannot find the link anywhere and no longer affects the behavior of the program, therefore it is impossible to detect that they are collected and disposed of by the garbage collector.

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Make sure you do not keep a reference to the object so that it can be GCed.

 x = null;
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Currently, Dart programs are deployed as JavaScripts and are therefore limited to the JavaScript execution model. Take a look at this question , for example, which explains that the only way to remove objects in JavaScript is through the garbage collector. If you call remove or removeAt etc. on your connectedSquares and do not contain other links, this does what you are looking for.

For destructors, the same restrictions apply. If an object containing links to the "rectangle body and ports located at two ends" becomes inaccessible, everything that it refers to becomes also suitable for garbage collection - again, in the absence of other links.

In general, if you want to fully understand the semantics of Dart runtime, then (at the moment) you also need to understand JavaScript, look at the compiled code and learn by analogy.

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Some additional removal note.

JavaScript restrictions affect dart.

  • No link references available
    This is a javascript function and in part because of how garbage collection works in the browser: What is JavaScript garbage collection?
  • Missing weak link (for now)
    Another limitation of Java-script and due to the lack of access to the reference counter, the deletion itself is also not an option.
    Note. There is Expando, and although it is useful, it is not a weak reference equivalent. A weak link allows you to create ghost links that do not save the object: https://en.wikipedia.org/wiki/Weak_reference .
  • Missing destructor

    javascript does not have this, therefore it does not jerk off.

As others have pointed out, the limitations above are usually nothing.
Since the main eventloop can keep objects alive, careless coding can spawn a zombie object; Without a destructor or weakref, some links can accidentally escape your murderous hands and keep the object alive.

 import 'dart:html'; import 'dart:async'; import 'dart:developer'; void main() { var e = new XXX(); var ce = new CustomEvent('custom-event'); var s = new Stream.periodic(new Duration(microseconds: 10000),(count) { print(count); window.dispatchEvent(ce); return count; }); StreamSubscription ss = s.listen((count){print('stream runnig; ${count}_th run');}); // e.destroy(); // ss.cancel(); e = null; s = null; } class XXX{ StreamSubscription subscription; XXX(){ subscription = window.on['custom-event'].listen(event_handler); } void say_hi(){ print('hi'); print(this); } void event_handler(_){this.say_hi();} destroy(){ subscription.cancel(); } }

The above code prints below in a forever loop (unless you uncomment the two lines):

  .... hi VM33:1 Instance of 'XXX' VM34:1 stream runnig; 751_th run VM34:1 752 VM33:1 hi VM33:1 Instance of 'XXX' VM34:1 stream runnig; 752_th run ......

I don’t know if object e will be saved without printing (this), maybe only related objects are stored from the garbage collection.

In any case, with more complex code, manual cleaning is required, and I want one of the three missing functions to be there, but not.

Removal can really be difficult.

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