Dispose, When Is It Called

Dispose, when is it called?

I want to write a class that is
straightforward and very easy to use,
to make sure that every possible
resource is cleaned up. I don't want
to put that responsibilty to the user
of my class.

You can't do that. The memory management is simply not built to accomodate resources that are not memory specifically.

The IDisposable pattern is intended for developers as a way of telling an object when they are done with it, instead of having the memory management trying to figure that out by using things like reference counting.

You can use the Finalizer as a fallback for users who fail to dispose objects properly, but it doesn't work well as the primary method for cleaning up objects. To work smoothly objects should be disposed properly, so that the more costly Finalizer doesn't ever need to be called.

When does the Dispose Method get called?

You need to explicitly call Dispose on any objects that implement IDisposable. If you use the using() {} code construct the compiler will automatically call Dispose at the end of the using block.

A good pattern is to also track via a private boolean field whether dispose has been called or not, and if not call it from the objects finalizer (and also call GC.SuppressFinalize() from your Dispose method assuming that you handle all finalization tasks from there also).

when does dispose method is called in using block

The using statement ensures that Dispose is called even if an exception occurs while you are calling methods on the object. You can achieve the same result by putting the object inside a try block and then calling Dispose in a finally block; in fact, this is how the using statement is translated by the compiler. The code example earlier expands to the following code at compile time (note the extra curly braces to create the limited scope for the object):

Key part is the "achieve the same result by putting the object inside a try block and calling finally".

SqlCommand command = new SqlCommand(queryString, connection);
try {

      // your code here
} finally {

      command.Dispose();
}

From MSDN

How and Where to Call Dispose in Flutter

According to the documentation

dispose method

Called when this object is removed from the tree permanently.

Regarding a page, the dispose method is called when the page is removed from the navigation stack. Here is a good explanation of Navigation.

When your widget (page) extends StatefulWidget, it's not mandatory but you can override the dispose method to execute additional instructions depending on your need. The method is called automatically when the page is being removed from navigation tree. Override the method as following

@override
void dispose() {
  // your desired instructions here

  super.dispose(); // This will free the memory space allocated to the page
}

Nonetheless, the method void pagedispose() cannot be overridden as it ain't a known method of StatefulWidget

Why do we use the dispose() method in Flutter Dart code?

dispose method used to release the memory allocated to variables when state object is removed.

For example, if you are using a stream in your application then you have to release memory allocated to the stream controller. Otherwise, your app may get a warning from the PlayStore and AppStore about memory leakage.

When do we need to call Dispose() in dot net c#?

Rule of thumb: if a class implements IDisposable you should always call the Dispose method as soon as you have finished using this resource. Even better wrap it in a using statement to ensure that the Dispose method will be called even if an exception is thrown:

using (var reader = conn.ExecuteReader())
{
    ...
}

What exactly does calling Dispose do?

The IDisposableinterface is being called by several consuming classes and - as already stated by Dark Falcon - when you encapsulate the usage of your class in a using block. This makes it easier to keep your unmanaged resources clean.
But Disposeis just like any other method and not to be confused with destructors/finalizers (which is what you apparently expected it to be)

ASP MVC: When is IController Dispose() called?

Dispose is called after the view is rendered, always.

The view is rendered in the call to ActionResult.ExecuteResult. That's called (indirectly) by ControllerActionInvoker.InvokeAction, which is in turn called by ControllerBase.ExecuteCore.

Since the controller is in the call stack when the view is rendered, it cannot be disposed then.

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