Wpf command canexecute not updating ios 4 updating your device

One of the great parts about commands in WPF is that they know if they can currently execute or not.When they cannot execute, the control(s) that are set to execute the command will be disabled automatically.For example, if your application has no changed data, the Save toolbar button will automatically be disabled, assuming its Command property is set to the Save command.

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This happens at various times, such as when input focus shifts to another control, an item is selected in a list, etc.

You can also programmatically trigger this to happen by calling the Command Manager’s Invalidate Requery Suggested static method.

This all seems magical, dreamy, and almost too good to be true.

Here’s the hitch: this beautiful system of commands automatically notifying the UI that they cannot execute only works out-of-the-box for Routed Commands.

Requery Suggested += value; } remove { Command Manager.

Requery Suggested -= value; } } public void Execute(object parameter) { // Do something awesome.I had been merrily using WPF’s built-in support for the Command Pattern for ages (see Commanding Overview, MSDN Docs, and article on implementing the command pattern in WPF, Jeff Druyt)…If you simply implement ICommand and hook up, say, a Button’s Command property to reference that non-routed command, suddenly the Magical Love Machine comes to a grinding and screeching halt. Because by default WPF has no idea that your custom ICommand objects exist. Fortunately there is an easy solution to this problem.In your ICommand implementation, you make the Can Execute Changed event hook the Command Manager’s Requery Suggested event.I lifted this little trick straight from Reflector, as I perused the Routed Command class…class My Command : ICommand { public bool Can Execute(object parameter) { return maybe True Or False; } public event Event Handler Can Execute Changed { add { Command Manager.


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