On 1/14/2013 4:28 PM, Chris Angelico wrote:
On Tue, Jan 15, 2013 at 6:48 AM, <servekar...@gmail.com> wrote:I'd like to develop a small debugging tool for python programs.In Dynamic Slicing How can I find the variables that are accessed in a statement? And find the type of access (read or write) for those variables (in Python). ### Write: A statement can change the program state. ### Read : A statement can read the program state . **For example in these 4 lines we have: (1) x = a+b => write{x} & read{a,b} (2) y=6 => write{y} & read{} (3) while(n>1) => write{} & read{n} (4) n=n-1 => write{n} & read{n}
I would try compiling the source code to an ast (abstract syntax tree). See the ast module for how to do that and how to 'read' the resulting tree.
An interesting question. What's your definition of "variable"? For instance, what is written and what is read by this statement: self.lst[2] += 4 Is "self.lst" considered a variable? (In C++ etc, this would be a member function manipulating an instance variable.) Or is "self" the variable? And in either case, was it written to?
'self' is read, 'lst' is written to. What about:
self.lst.append(self.lst[-1]+self.lst[-2]) (which might collect Fibonacci numbers)?
'self' read, 'lst' read and written. Knowing that for non-builtins is another matter ;-).
-- Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
