Testing the availability of a module

[Fredrik Lundh]

Bo Peng wrote:

> > here's an outline that matches your use case:
> >
> >     if user wants command line:
> >         command line only
> >     else:
> >         if wxPython is available:
> >             prepare wx based GUI
> >         elif Tkinter is available:
> >             prepare tk based GUI
> >         else:
> >             command line only
>
> This is exactly the logic I use,... Eliminating all unrelated stuff, I
> have something like (thanks for the imp hint):
>
> def wxGUI():
>    import wx
>    wx...
>
> def tkGUI():
>    import Tkinter as tk
>    tk....
>
> def cml():
>    command line
>
> def GUI():
>    if options['cml']:
>      cml()
>    else:
>      if imp.find_module('wx'):

that imp call is completely unnecessary, and means that you'll scan
the path *twice* for each module, instead of once.

this is more efficient:

    try:
        wxGUI()
    except ImportError:
        try:
            tkGUI()
        except ImportError:
            cml()

</F>