Operator # WeakAddressOf

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Operator --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ## Description Creates a `Delegate`, just like `AddressOf` does, with the difference that it references the method's object instance using a WeakRef internally. ## Usage ``` xojo delegate = WeakAddressOf methodName ``` | Part | Description | |-------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | `Delegate` | A `delegate` that references *methodName*. The `Delegate` automatically converts to a `Ptr`. | | methodName | The method to which you want a pointer. | ## Notes It can only be used with instance methods of classes, not with shared methods and global methods from modules (use `AddressOf` for those). If the delegate method is invoked after the object has been destroyed, an exception will be raised. WeakAddressOf and `AddressOf` are operators, not functions, and cannot be used with parentheses. For example, *WeakAddressOf(someMethod)* leads to an error. Use *WeakAddressOf someMethod* instead. ## Sample code This example lets you handle the Timer.Action (Desktop & Console projects) event without creating a Timer subclass. Start by adding a property to the layout: ``` xojo MyTimer As Timer ``` --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Next, add a ProgressBar to the layout. The Timer will update the ProgressBar.

Note

This example is using a `DesktopProgressBar` which has slightly different properties than a `MobileProgressBar` or `WebProgressBar`.

In the Opening event handler of the layout, instantiate the Timer and indicate that its Action event handler should be handled by a method, TimerAction, that you will add to the layout: ``` xojo MyTimer = New Timer MyTimer.Period = 1000 MyTimer.RunMode = Timer.RunModes.Multiple AddHandler MyTimer.Action, WeakAddressOf TimerAction ``` --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Now add the TimerAction method to the layout: ``` xojo Sub TimerAction(sender As Timer) If ProgressBar1.Value < ProgressBar1.MaximumValue Then ProgressBar1.Value = ProgressBar1.Value + 1 Else ' Stop Timer and Remove the handler sender.RunMode = Timer.RunModes.Off RemoveHandler MyTimer.Action, WeakAddressOf TimerAction End If End Sub ``` ## Compatibility | | | |-----------------------|-----| | **Project Types** | All | | **Operating Systems** | All |

`MemoryBlock` function; `AddHandler`, `AddressOf`, `Declare` statement; `Delegate`, `Ptr` data types; `Operator Precedence`.