WPFCustomControls::RequeryableCommandAdapter Class Reference

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Detailed Description

Intermediate abstract base class automatically requesting CanExecute reevaluation when the CommandManager fires a RequerySuggested event.

WPF Controls such as Buttons or MenuItems may only reevaluate their Command's CanExecute state upon receiving a CanExecuteChanged event. These Controls use the CanExecute result to determine their own Enabled state. The WPF CommandManager uses the RequerySuggested event to request that ICommands reevaluate their execution conditions. Clients may force such a reevalation using CommandManager.InvalidateRequerySuggested.

RoutedCommands listen to CommandManager.RequerySuggested by default, but custom ICommands do not. This base class encapsulates the behavior required to signal CanExecuteChanged when the CommandManager raises a RequerySuggested event such that concrete classes may inherit and reuse this behavior.

List of all members.

Public Member Functions
	RequeryableCommandAdapter ()
	Construct this ICommand and register a CommandManager.RequerySuggested listener.
abstract bool	CanExecute (object parameter)
	Determine if the conditions under which this ICommand can execute are valid.
abstract void	Execute (object parameter)
	Execute this ICommand's operation.
Protected Member Functions
virtual void	OnCanExecuteChanged (EventArgs e)
	Raises a CanExecuteChanged event.
Events
EventHandler	CanExecuteChanged
	Signals that the conditions under which this ICommand can execute have changed.

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Constructor & Destructor Documentation

WPFCustomControls::RequeryableCommandAdapter::RequeryableCommandAdapter

(

)

[inline]

Construct this ICommand and register a CommandManager.RequerySuggested listener.

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Member Function Documentation

abstract bool WPFCustomControls::RequeryableCommandAdapter::CanExecute

(

object

parameter

)

[pure virtual]

Determine if the conditions under which this ICommand can execute are valid.

Parameters:

parameter

Data used by the command.

Returns:

True if this command can be executed; otherwise, false.

abstract void WPFCustomControls::RequeryableCommandAdapter::Execute

(

object

parameter

)

[pure virtual]

Execute this ICommand's operation.

Parameters:

parameter

Data used by the command.

virtual void WPFCustomControls::RequeryableCommandAdapter::OnCanExecuteChanged

(

EventArgs

e

)

[inline, protected, virtual]

Raises a CanExecuteChanged event.

Parameters:

e	Information about the CanExecuteChanged event.

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Event Documentation

EventHandler WPFCustomControls::RequeryableCommandAdapter::CanExecuteChanged

Signals that the conditions under which this ICommand can execute have changed.