[Pythoncard-users] auto-persistance and New/Open/Save document models

[Kevin A. <al...@se...>]

Both the textEditor and resourceEditor samples are using essentially the
same logic for managing user config files and the "state machine" logic for
New, Open, Save, Save As..., Revert, Exit. This is different than the logic
most of the other samples use which is like the HyperCard auto-persistance
model, where a data file is automatically opened when the app starts up and
the data file is automatically saved when the app closes. The latter code is
much simpler as this fragment from the addresses sample shows:

    def on_openBackground(self, source, event):
        if not outlook.WIN32_FOUND:
            self.menuBar.setEnabled('menuFileImportOutlook', 0)

        if os.path.exists(USER_DATA_FILE):
            self.document = Document(self, USER_DATA_FILE)
        else:
            self.document = Document(self, DATA_FILE)
            # make sure we don't overwrite the default file from cvs
            self.document.filename = USER_DATA_FILE

    def doExit(self):
        self.document.saveFile()

    # we don't have window events hooked up yet to our own event model yet
    def OnCloseWindow(self, event):
        self.doExit()
        model.Background.OnCloseWindow(self, event)

    def on_exit_command(self, menu, event):
        self.Close()

The Document class actually handles the opening and saving of the data file,
so the background "view" doesn't contain that code. The if/then/else in the
openBackground handler should probably be changed so the Document is
responsible for deciding how it gets the initial data, then the "view" won't
care whether the data comes from ZODB, a text file, a remote web site, etc.

It would probably be worthwhile having other coders go over the logic for
both types of app models, discussing it on the list to improve the code (I
admit it is a bit of a hack job) and then moving the code into separate
classes. These could be subclasses of Background or more likely separate
classes that are used via multiple inheritance.

ka