How can I create a GUI on top of a Python APP so it can do either GUI or CLI?

Question

I am trying to write an app in python to control a motor using serial. This all works in a CLI situation fine and is generally stable. but I was wondering how simple it was

Answer 1

is there a simple way of detecting something like GTK, so it only applied the code when GTK was present?

First, break your app into 3 separate modules.

1. The actual work: foo_core.py.

2. A CLI module that imports foo_core. Call it foo_cli.py.

3. A GUI module that imports foo_core. Call it foo_gui.pyw.

The foo_cli module looks like this.

import foo_core
import optparse

def main():
    # parse the command-line options
    # the real work is done by foo_core

if __name__ == "__main__":
   main()

The foo_gui module can look like this.

 import foo_core
 import gtk # or whatever

 def main()
     # build the GUI
     # real work is done by foo_core under control of the GUI

 if __name__ == "__main__":
     main()

That's generally sufficient. People can be trusted to decide for themselves if they want CLI or GUI.

If you want to confuse people, you can write a foo.py script that does something like the following.

try:
    import foo_gui
    foo_gui.main()
except ImportError:
    import foo_cli
    foo_cli.main()