Type feedback tool?

[skip at pobox.com]

(Sorry for any repeated recommendations.  I'm offline until Monday morning.
You may well see some of these suggestions in the meanwhile, but so far it
seems you've had no nibbles.)

    Martin> I'm wondering if there's a tool that can analyze a Python
    Martin> program while it runs, and generate a database with the types of
    Martin> arguments and return values for each function. 

Nothing that I'm aware of.  Here are a few ideas though.

1. Modify the source code in question to decorate any functions you're
   interested in, e.g.:

    #!/usr/bin/env python

    class ZeroDict(dict):
        def __getitem__(self, key):
            if key not in self:
                return 0
            return dict.__getitem__(self, key)

    _argtypes = ZeroDict()

    def note_types(f):
        "Decorator that keeps track of counts of arg types for various functions."
        def _wrapper(*args):
            _argtypes[(f,) + tuple([type(a) for a in args])] += 1
            return f(*args)
        return _wrapper

    @note_types
    def fib(n):
        if n < 0:
            raise ValueError, "n < 0"
        if n > 1:
            return fib(n-1) + fib(n-2)
        return 1

    @note_types
    def fib2(n):
        "fib() that guarantees it is dealing with ints."
        if n < 0:
            raise ValueError, "n < 0"
        n = int(n)
        if n > 1:
            return fib2(n-1) + fib2(n-2)
        return 1

    if __name__ == "__main__":
        print "fib(5) ==", fib(5)
        print "fib(4.0) ==", fib(4.0)
        print "fib2(5) ==", fib2(5)
        print "fib2(4.0) ==", fib2(4.0)
        print _argtypes

   You can probably write a source transformation tool to decorate all
   functions (or just use Emacs macros for a 99% solution which takes a lot
   less time).

2. Look at tools like pdb.  You might be able to add a new command to
   decorate a function in much the same way that you might set a breakpoint
   at a given function.

3. Take a look at IDEs with source (like IDLE).  You might be able to coax
   them into decorating functions then display the collected statistics when
   you view the source (maybe display a tooltip with the stats for a
   particular function).

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