An easy solution to all of this is to use a dict-like object that
matches keys based on object identity while ignoring __hash__ and
__eq__ entirely, e.g.:
https://bitbucket.org/pypy/pypy/src/2f51f2142f7b/lib_pypy/identity_dict.py#c...
-n
On Wed, Apr 10, 2013 at 10:45 AM, Sebastian Berg
On Wed, 2013-04-10 at 11:54 +0300, Dmitrey wrote:
You think comparing tracked bug counts across different projects means anything? That's adorable. I admire your diligence at addressing the bugs that you do acknowledge. That was never in question. But refusing to acknowledge a bug is not the same thing as fixing a bug. You cannot use objects that do not have a valid __eq__() (as in, returns boolean True if and only if they are to be considered equivalent for the purpose of dictionary lookup, otherwise returns False) as dictionary keys. Your oofun object still violates this principle. As dictionary keys, you want them to use their `id` attributes to distinguish them, but their __eq__() method still just returns another oofun with the default object.__nonzero__() implementation. This means that bool(some_oofun == other_oofun) is always True regardless of the `id` attributes. You have been unfortunate enough to not run into cases where this causes a problem yet, but the bug is still there, lurking, waiting for a chance hash collision to silently give you wrong results. That is the worst kind of bug. -- Robert Kern I had encountered the bugs with bool(some_oofun == other_oofun) when it was raised from other, than dict, cases, e.g. from "in list" (e.f. "if my_oofun in freeVarsList") etc, and had fixed them all. But that one doesn't occur from "in dict", I traced it with both debugger and
On 04/10/2013 10:31 AM, Robert Kern wrote: putting print("in __eq__"),print("in __le__"), print("in __lt__"), print('in __gt__'), print('in __ge__') statements.
This is all good and nice, but Robert is still right. For dictionaries to work predictable you need to ensure two things.
First:
if object1 == object2: assert bool(hash(object1) == hash(object2))
and second, which is your case for the dictionary lookup to be predictable this must always work:
keys, values = zip(*dictionary.keys()) assert(keys.count(object2) == 1)
index = keys.index(object2) value = values[index]
And apparently this is not the case and it simply invites bugs which are impossible to track down because you will not see them in small tests. Instead you will have code that runs great for toy problems and can suddenly break down in impossible to understand ways when you have large problems.
So hopefully the list fixes you mention provide that the second code block will work as you would expect dictionary[object2] to work, but if this is not the case...
- Sebastian
As I had mentioned, removing mapping oofuns as dict keys is mere impossible - this is fundamental thing whole FuncDesigner is build on, as well as its user API. D.
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