will python 3000 break my code?
echuck at mindspring.com
Thu Mar 2 04:23:48 CET 2000
So I came into this discussion very late. What is Python 3000? :-)
(Seriously, got a URL or posting or something? My earliest article in this thread doesn't clue me in.)
Daniel Berlin wrote:
> >>>>> "MF" == Martijn Faassen <m.faassen at vet.uu.nl> writes:
> MF> [snip]
> MF> [effbot]
> >> 3. be impossible to identify by automatic tools. Tim's excellent
> >> checkappend.py can spot many cases, but not all.
> >> Actually, this isn't true (that it's impossible). If you really like,
> >> i'll take a few days of my spring break and write one guaranteed to
> >> catch every single case. You can do it by looking at the byte code.
> >> If you are trying to call function "append" with more than 1 argument
> >> on an object whose type is a list, it's bad.
> MF> Are you sure you've thought this through? How would you know the type
> MF> of an object is a list?
> This can only be done at runtime, of course, without getting into very heavy
> However, i can instrument the code rather easily, so that even really tricky
> things would still tell you where the problem is really being generated (IE
> where foo became an append method, which is why when you passed it to some
> random function that called it's arguments, you had problems.
> That's the only way to catch things passed as arguments.
> I was talking about a tool that both looked at the bytecode, and instrumented
> It's automatic in the same way "BoundsChecker" is an automatic tool.
> MF>That's the tricky part, to know you're dealing
> MF> with a list and not something else that happens to have a method
> MF> 'append'.
> I realize this.
> MF> Anyway, if you can write a static typechecker for Python in a few days
> MF> during spring break the types-sig will be happy; doing this isn't
> MF> *that* much easier than writing a full fledged static typechecker, it
> MF> seems to me.
> God no. I shudder at the thought of the analysis required.
> MF> Regards,
> MF> Martijn
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