On Oct 1, 2012, at 9:11 AM, Jim Bosch wrote: > On 09/30/2012 03:59 PM, Travis Oliphant wrote: >> Hey all, >> >> In a github-discussion with Gael and Nathaniel, we came up with a proposal >> for .base that we should put before this list. Traditionally, .base has >> always pointed to None for arrays that owned their own memory and to the >> "most immediate" array object parent for arrays that did not own their own >> memory. There was a long-standing issue related to running out of stack >> space that this behavior created. >> >> Recently this behavior was altered so that .base always points to "the >> original" object holding the memory (something exposing the buffer >> interface). This created some problems for users who relied on the fact >> that most of the time .base pointed to an instance of an array object. >> >> The proposal here is to change the behavior of .base for arrays that don't >> own their own memory so that the .base attribute of an array points to "the >> most original object" that is still an instance of the type of the array. >> This would go into the 1.7.0 release so as to correct the issues reported. >> >> What are reactions to this proposal? >> > > In the past, I've relied on putting arbitrary Python objects in .base in > my C++ to NumPy conversion code to make sure reference counting for > array memory works properly. In particular, I've used Python CObjects > that hold boost::shared_ptrs, which don't even have a buffer interface. > So it sounds like I may be a few steps behind on the rules of what > actually should go in .base. >
This should still work, nothing has been proposed to change this use-case. > I'm very concerned that if we do demand that .base always point to a > NumPy array (rather than an arbitrary Python object or even just one > with a buffer interface), there's no longer any way for a NumPy array to > hold data allocated by something other than NumPy. I don't recall a suggestion to demand that .base always point to a NumPy array. The suggestion is that a view of a view of an array that has your boost::shared_ptr as a PyCObject pointed to by base will have it's base point to the first array instead of the PyCObject (as the recent change made). > > If I want to put external memory in a NumPy array and indicate that it's > owned by some non-NumPy Python object, what is the recommended way to do > that? The approach you took is still the way I would recommend doing that. There may be other suggestions. -Travis _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
