Recursion limit problems

[Terry Reedy]

"elventear" <elventear at gmail.com> wrote in message 
news:1178921877.442519.165740 at u30g2000hsc.googlegroups.com...
| Hello everyone,
|
| I am runing into recursion limit problems. I have found that the
| culprit was related to the __hash__ function that I had assigned to
| the objects that were added to a set.
|
| Basically my __hash__ function is the following:
|
| def __hash__(self):
| out_int = 0
| for property,value in self:
| out_int ^= hash( property )^hash( value )
|
| return out_int
|
| And the iterator for this object is:
|
| def __iter__(self):
| for property,value in self.__dict__.iteritems():
| yield property,value
|
| After commenting the __hash__ function and using the default provided
| by Python (I suppose it is based on the position in memory of the
| object), the recursion limit problems went away. (This problem was
| happening even after increasing the recursion limit to the maximum of
| my platform, MacOSX).
|
| I am not that versed in Python, so I don't know exactly I could do to
| overcome this problem, any ideas are deeply appreciated.

Without seeing the full code and the exception traceback, my guess is that 
your __hash__ somehow calls itself due to a refence loop in your object.  A 
simple example of a loop:
a = []; a.append(a)
Now, list objects are not hashable, but if they were, and the hash were 
value based (like your), then hash(a) would call hash(a) would call 
hash(a)....

Suggestion: put print id(self) in __hash__ and see if you get a repeat.
And maybe reduce the recursion limit to reduce the traceback listing ;-)

Terry Jan Reedy