[PEAK] Problem with peak.rules and Python < 2.5

[Phillip J. Eby]

At 11:42 PM 6/19/2008 +0200, Christoph Zwerschke wrote:
>Please have a look at the following code:
>
>----------------------------
>
>import sys
>from peak.rules import when
>
>class X:
>     pass
>
>class Y(X):
>     pass
>
>x = Y()
>
>f = lambda x: "f"
>
>g = when(f, "isinstance(x, X)")(lambda x: "g")
>
>print sys.version.split()[0], isinstance(x, X), f(x)
>
>-----------------------------
>
>It is expected to print "g", but it prints "f" for Python < 2.5:
>
>2.3.5 True f
>2.4.4 True f
>2.5.2 True g
>
>It seems "isinstance" does not work with multilevel inheritance in 
>peak.rules for Py < 2.5. Is this a known problem? Can it be fixed?

That's quite odd - I found the problem to occur in all versions of 
Python, for the PEAK-Rules trunk...  it's a breakage resulting from 
the index refactoring I did last week.  Are you sure you're running 
identical versions of PEAK-Rules across Python versions?

In the meantime, I've added a test for this, and the fix.