Change Program Flow based on Available Libraries

Question

I am developing a Python model that will support graphing if the correct modules are installed. I would like the source code to be the same if possible, IE, if the graphing model can't load, graphing would be ignored from the menu logic.

How can I accomplish this?

Answer 1

Attempt an import and set a flag if fails. Then use the flag to determine whether to offer graphic output:

try:
    import Tkinter
    gui_installed = True
except ImportError:
    gui_installed = False


...

result = somecalc()
if gui_installed:
    display_with_gui(result)
else:
    display_as_text(result)

Answer 2

Yes. You can wrap an import statement in a try-except block. It is commonly used for backwards-compatability cruft. For instance, by importing a fall-back module as the desired module. That way the rest of the code can be oblivious to which module is actually in use.