TopSort in Python?

[duncan smith]

Carl Banks wrote:
> On Jan 18, 7:01 pm, Paddy <paddy3... at googlemail.com> wrote:
>> On Jan 18, 9:47 pm, startec... at gmail.com wrote:> Tim,
>>
>>> Thanks for the topsort code.  It would be useful in a project I'm
>>> working on.  Can I use the code for free under public domain?  Thanks!
>> When I needed one I didn't know the name. I'm curious, how did you
>> know to look for the topological sort algorithm by name?
> 
> I spent quite a bit of time looking for this one myself.  It was quite
> a stumper.  Sometimes Google gets us in the habit of just firing
> random search terms when we ought to be thinking it out.
> 
> After quite of bit of dead end searching--like a week--I stepped back,
> thought about what I was looking for.  I wanted a sort of dependency
> system: A must happen before B.  What other programs do that?  make,
> of course.  I looked at the documents for make and found the term
> "directed acyclic graph", and pretty much instantly knew I had it.

Searching for "precedence diagram" might throw up some relevant results; 
but you've probably already discovered that.  I have some basic 
precedence diagram code (no warranty etc.) somewhere if anyone is 
interested.

Duncan