[IronPython] IronPython 2: Bug in Indexing (Blocker)

[Michael Foord]

Dino Viehland wrote:
> Thanks for the report.  I've opened CodePlex bug #19350 to track this (http://www.codeplex.com/IronPython/WorkItem/View.aspx?WorkItemId=19350).
>
> I believe the fix is actually pretty simple and we'll discuss whether we'll take it for 2.0 final at our Friday team meeting.  If you want to try out the fix either to unblock yourself or just see if there's other issues lurking behind it you can do this change:
>   

Thanks Dino - that fix certainly fixes the specific issue and means I 
have less failing tests in my Worksheet test (and no new ones as far as 
I can tell).

Although Resolver One now runs on IronPython 2 I'm still in a position 
where there are a stack of failing tests (we have 6000 tests in total 
and I'm gradually moving through them working out whether failures are 
because we are testing against the old API, failures that indicate bugs 
in IronPython, failures due to moving to Python 2.5, or anything else...)

Although aspects of Resolver One on IronPython 2 are just as fast as 
they are on IronPython 1 there are still some specific performance 
issues. We anticipate that the hardest part of the port will be 
identifying and fixing those issues (thankfully we have a bunch of 
performance tests to help us). If we find anything specific we will 
report it back of course.

We would appreciate this fix being in 2.0 final as it is our goal to do 
a new Resolver One release based on it as soon as humanly possible, and 
we would prefer not to have to rely on a patched version.

Anyway - thanks for identifying a fix so quickly.

All the best,

Michael

>                           return new MetaObject[] {
>                         arguments[0],
>                         new MetaObject(
>                             Ast.Call(
>                                 typeof(PythonOps).GetMethod("MakeTuple"),
>                                 Ast.NewArrayInit(typeof(object), tupleArgs)
>                             ),
> -                           Restrictions.Empty
> +                           Restrictions.Combine(arguments)
>                         ),
>                         arguments[arguments.Length-1]
>                     };
>
> If you just search for "return new MetaObject[]" in PythonProtocol.Operations.cs you'll get to the right spot.  There's a 2nd spot about 20 lines later for the getter case which has the same issue & fix.
>
> -----Original Message-----
> From: users-bounces at lists.ironpython.com [mailto:users-bounces at lists.ironpython.com] On Behalf Of Michael Foord
> Sent: Wednesday, November 05, 2008 8:03 AM
> To: Discussion of IronPython
> Subject: [IronPython] IronPython 2: Bug in Indexing (Blocker)
>
> Hello Guys,
>
> Discovered a bug in indexing Python objects in IronPython 2.
>
> The following code:
>
> class X(object):
>     def __setitem__(self, key, value):
>         print repr(key)
>
> def f(a, b):
>     X()[a, b] = object()
>
> f(1, 2)
> f('one', 'two')
>
> Produces the following exception:
>
> Traceback (most recent call last):
>   File "bugtest.py", line 9, in bugtest.py
>   File "bugtest.py", line 6, in f
> TypeError: Specified cast is not valid.
>
> It looks like IronPython has a call site that is now expecting integers
> the second time round.
>
> Switching to using explicit tuples for indexing works around the problem:
>
>     X()[(a, b)] = object()
>
> However this kind of indexing is an *extremely* common way to use our
> spreadsheet API from user code, so we couldn't release with this bug in
> place.
>
> (Doing the indexing outside of the function also avoids the problem
> interestingly enough.)
>
> All the best,
>
> Michael Foord
>
> --
>
> Michael Foord
> Senior Software Engineer, Resolver Systems Ltd.
> michael.foord at resolversystems.com
> +44 (0) 20 7253 6372
>
> Try out Resolver One! <http://www.resolversystems.com/get-it/>
>
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