Factor out menu choice

[toonarmycaptain]

The code for taking user input to choose and run items from menus in main_menu.py and settings_menu.py deploy similar functionality which can be factored out.

take_settings_menu_input was recently refactored here and here not to use a flag to break the loop, matching the implementation in main_menu.py:

dionysus/dionysus_app/UI_menus/settings_menu.py

Lines 41 to 55 in 6046e12

	possible_options = {
	'1': call_set_default_chart_save_location,
	# '0': return_to_main_menu,
	}
	while True:
	chosen_option = input('>>> ')
	if chosen_option in possible_options:
	possible_options[chosen_option]()
	break # Exit loop when chosen action finishes. Returns None.
	if chosen_option == '0': # User selects to return to main menu.
	return True
	# else:
	print("Invalid input.")

)

To generalise the function I propose reintroducing a flag, returned by the functions corresponding to the options in a menu, that would indicate a return to a higher menu/scope.
This also reintroduces using a function for breaking the loop/menu without action, as originally implemented in settings_menu.py (albeit with stdout user feedback).

This would allow any function to break the take/run menu selection loop with a flag returned to the calling menu logic, which may have a variety of uses - for example returning False if the action was unsuccessful could trigger feedback to the user before displaying the menu again eg Action unsuccessful. Please select another option: {menu options}. These implementations make assumptions about what the called functions return:

Assume only True is a relevant return value:

while True:
    chosen_option = input('>>> ')

    if chosen_option in possible_options:
        if possible_options[chosen_option]():  # or more explicitly: if possible_options[chosen_option]() is True:
            return True
        break  # Exit loop when chosen action finishes. Returns None.
    # else:
    print("Invalid input.")

Or to be able to return True or False flags:
Assumes True and False are relevant return values.

while True:
    chosen_option = input('>>> ')

    if chosen_option in possible_options:
        return_flag = possible_options[chosen_option]()
        if return_flag is not None:
            return return_flag
        break  # Exit loop when chosen action finishes. Returns None.
    # else:
    print("Invalid input.")

Alternatively, assuming functions will return None, True or False - or equivalent values :
A weakness of this approach is that there is a risk of bugs creeping in where functions happen to return an object (eg str, dict) that evaluates to True/False/None that the caller will then interpret as those values - which may be useful, or a source of bugs.

while True:
    chosen_option = input('>>> ')

    if chosen_option in possible_options:
        return possible_options[chosen_option]()
    # else:
    print("Invalid input.")

While the above is very elegant/simple, a more explicit implementation might be preferable:

while True:
    chosen_option = input('>>> ')

    if chosen_option in possible_options:
        return_flag = possible_options[chosen_option]()
        if return_flag is True or return_flag is  False or return_flag is  None:
            return return_flag
        break  # Exit loop when chosen action finishes. Returns None.
    # else:
    print("Invalid input.")

[toonarmycaptain]

GitMate.io thinks a possibly related issue is #122 (Factor out UI elements).

[toonarmycaptain]

In retrospect probably better to leave the menus as is. Use settings_menu as a pattern for other menus, move that general function to UI_functions, and have all menus, aside from the main menu, use a '0' entry to return to upper scope/menu.
Alternatively, run quit_app as a function from main_menu. Have quit_app also run after run_main_menu if you press '0' (although that option is not listed) and break out of main_menu, with an "are you sure you want to quit" wrapper.
Probably fine to call run_main_menu again on 'no I didn't really want to quit' if calling after main_menu and didn't really want to quit. Unless user is particularly silly and does this a bunch of times, there won't be an issue with too many nested calls.