FYI this is a completely hypothetical situation here. I am not doing any developing in the Python/C API, and may never do so. But I'm experimenting with different levels of architecture, mainly just to see how things work. Right now the situation is, suppose I have some function I want to call from Python, but in the end I want to implement it in basically raw C. One approach I thought of was, okay, I'll Pyrex a really simple function, compile it and go into the c file, then write most of what I need from there. My main thought about reference counting:
Python objects seem to need heavy babysitting in terms of reference counting, especially if you look at some Pyrex autogen code. But it seems like the C compiler will keep track of reference counts for C types. Just supposing (again, completely hypothetical) I decide to write something in the P/C API completely without Pyrex or SageX, but I want a Python function or two to get called at the top, and I want C to do the rest. My impression is that I need to keep track of reference counts for PyObjs but not C variables. Is this true? I have never had to worry about reference counting when writing pure C, so why do PyObjects need that extra help? On Feb 21, 10:57 am, Robert Bradshaw <[EMAIL PROTECTED]> wrote: > I'll jump in and answer you questions. > > On Feb 21, 2007, at 10:18 AM, Robert Miller wrote: > > > David, > > > I was wondering if you could help get me started here. I've been > > reading the Python/C API, and I've been browsing both sides of a lot > > of Pyrex: for argument's sake, let's say the Complex double matrices. > > First, I'm wondering how they're cdef-ing classes that they're then > > calling from Python. > > cdef has two uses. The first is to declare a class as an extension > type (so it can contain cdef'd property and functions), and the > second is to declare a property/function as a c type. Cdef'd > extension types are accessible from python, just not their cdef'd > properties/functions. > > > Also, what do .so files in site-packages have to > > do with specific classes in the repository? > > > ( > > sage: > > sage.matrix.matrix_complex_double_dense.Matrix_complex_double_dense?? > > Type: type > > Base Class: <type 'type'> > > String Form: <type > > 'sage.matrix.matrix_complex_double_dense.Matrix_complex_double_dense'> > > Namespace: Interactive > > File: > > /Volumes/DATA/sage/local/lib/python2.5/site-packages/sage/matrix/ > > matrix_complex_double_dense.so > > ) > > Each .pyx file has an associated shared object library containing all > the classes/methods/etc. needed. > > > > > I have some questions also about reference counting, but let's > > start here..... > > You shouldn't have to worry about it too much. Basically, if you > malloc something manually, you have to worry about freeing it. If you > call the C/Python API directly (which you probably won't need to do), > you have to worry if the returned PyObject* is a borrowed or new > copy. But otherwise pyrex will take care of it all for you. > > > > > -- > > Robert L. Miller > >http://www.robertlmiller.com/ --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
