[Tutor] Loop-checking question

[Kent Johnson]

Alan Gilfoy wrote:
> My programs often have long, detailed loops in them, and would like  
> to, as I'm executing the loop, view what part of the loop Python is  
> currently processing.
> 
> Thus, if my program gets stuck in one part of the loop, I would see that.
> Thus, if one part of my loop is never triggered, I would see that.
> 
> I could use, within my loop, print 'I am here, at part X of the loop',  
> but I believe that would be far to clunky to put in every section of  
> my program's loop(s).

I'm not really sure what you expect this view to look like. I don't know 
of any tool that will let you dynamically watch a program as it 
executes. Some alternatives:

- A debugger lets you step through the code and see how it behaves. 
winpdb is a pretty nice GUI-based Python debugger and some Python 
development tools have built-in debuggers.
http://www.digitalpeers.com/pythondebugger/

- If the program is stuck in a loop, pressing control-C will abort the 
loop and give a stack trace showing you where it was.

- The Python profiler will tell you (after the fact) how much time you 
spend in each function. To see what part of a loop the program is in you 
would have to break the loop up into functions.
http://docs.python.org/lib/profile.html

- A code coverage tool will tell you (after the fact) which lines of the 
program were executed and which were not. (google python code coverage)

Kent