Question

When using ICommands in XAML, WPF uses the CanExecute method to enable or disable controls associated with the command. But what if I am calling Execute from procedural code? Should I first check CanExecute to make sure that the command can execute, or should Execute take care of this check for me?

In other words, should I do this:

if (someCommand.CanExecute(parameter, target))
    someCommand.Execute(parameter, target);

Or just this:

someCommand.Execute(parameter, target);

Answer 1

Good style would dictate that you should do the former, check CanExecute first. This will enforce proper decomposition and a consistency in implementation. Also, in the event you ever do want to use this command bound to a button, it will work as expected.