Prompt to install missing software?

[John Pye <john@curioussymbols.com>]

Hi all,

I have a PyGTK-based program that has an optional dependency on the
package python-matplotlib.

Is there any way under Debian (and hopefully also Ubuntu) that I can
trigger gtk-debi or something like that when the user requests to use
the part of my program that depends on stuff they haven't installed yet?
What would be the best way of doing that from python, if such a thing
exists?

I believe I have seen this used somewhere but I don't know how it was done.

Cheers
JP