Next step after pychecker

[Philippe Fremy]

	Hi,

I would like to develop a tool that goes one step further than pychecker 
to ensure python program validity. The idea would be to get close to 
what people get on ocaml: a static verification of all types of the 
program, without any kind of variable declaration. This would definitely 
brings a lot of power to python.

The idea is to analyse the whole program, identify constraints on 
function arguments and check that these constraints are verified by 
other parts of the program.

What is in your opinion the best tool to achieve this ? I had an 
extensive look at pychecker, and it could certainly be extended to do 
the job. Things that still concern me are that it works on the bytecode, 
which prevents it from working with jython and the new .NET python.

I am currently reading the documentation on AST and visitor, but I am 
not sure that this will be the best tool either. The AST seems quite 
deep and I am afraid that it will make the analysis quite slow and 
complicated.


For a simple pattern of what I want to do:

def f1( a ):
	return a+1

def f2():
	f1( [] )

Obviously, this won't work, but neither pychecker nor the python 
interpreter will catch it. But a program analysis can catch it in this 
simple example.

	regards,

	Philippe