uicommand: interfacing commands with UI elements

Whereas Command object encapsulate something that happens to the model, UICommand objects are associated to an UI element and are triggered by it (it’s actually a subclass of QAction). They will typically create a new Command and run it in their do() method, each time it’s invoked.

Integration of commands with UI elements

class pyqtcmd.uicommand.NeedsSelectionUICommandMixin(parent=None, *, container, **kwargs)

A mixin for UICommand. The constructor takes a container keyword argument. This must be an object which implements a selectionChanged signal (of any signature) and a selection() method, which should return the selection as an object with a __len__.

container()

Accessor for the underlying container

selection()

Returns the current selection. If you want to implement more drastic limitations than ‘selection is not empty’ you can override this to filter the actual underlying selection. The action will be enabled iff this returns a non-empty iterable.

class pyqtcmd.uicommand.RedoUICommandMixin(*args, text=None, **kwargs)

Redo UICommand. This is a mixin so you can inherit from your concrete UICommand subclass.

class pyqtcmd.uicommand.UICommand(parent=None, *, text=None, icon=None, shortcut=None, tip=None)

An UICommand is the intermediate between UI elements and the underlying Commands. A Command encapsulates a single behavior; an UICommand has a longer life time since it’s associated to a UI element. Its role is to instantiate and run the right Command when the user interacts with the element. It also has an enabled/disabled state that you can manage by overriding the should_be_enabled() method.

add_signal_check(signal)

Call this, passing it a signal that could change the UIAction state (enabled/disabled, etc) when it’s fired. The signal’s signature does not matter.

do()

Subclasses should override this to do whatever is necessary (for instance show a dialog for choosing a file name, etc) and then instantiate the right Command class and run() it.

history()

Override this to return the History object

set_button(btn)

Associates this command to a push button.

should_be_enabled()

Return False from this method if the underlying UI element should be disabled.

class pyqtcmd.uicommand.UndoUICommandMixin(*args, text=None, **kwargs)

Undo UICommand. This is a mixin so you can inherit from your concrete UICommand subclass.