Mastering Perl/Tk

The TextUndo Widget

The TextUndo widget is derived from the Text widget, which simply means that it shares all the capabilities of its ancestor. In object-oriented terminology, we say that TextUndo is a subclass of Text (or, Text is a superclass of TextUndo). You’ll learn more about this subject in Chapter 14.

Of course, we expect TextUndo to do something different from Text, and it does: it has unlimited undos and redos so that previous editing operations can be rescinded or redone.

Here are the TextUndo methods above and beyond those available for a Text widget:

$textundo->ConfirmDiscard

Displays a messageBox that says “Save edits?”. Returns 0 if yes or cancel, 1 if no.

$textundo->ConfirmEmptyDocument

Displays a messageBox that says “Save edits?.” The widget is cleared if the reply is no.

$textundo->ConfirmExit

Destroys the widget if you answer yes.

$textundo->CreateFileSelect

Creates a popup file browser to select a filename.

$textundo->deleteStringAtStartOfSelectedLines( string )

Deletes string from the start of every selected line.

$textundo>->EmptyDocument

Deletes all text and undo/redo information; undefs the filename.

$textundo->FileName(? pathName ?)

Optionally updates the current filename to pathName. Returns the current filename.

$textundo->IncludeFile

Similar to Load, except it does not call EmptyDocument first.

$textundo->insertStringAtStartOfSelectedLines( string )

Inserts string at the start of every selected line.

$textundo->Load( pathName )

Loads the contents ...