On Sunday, 10 February 2019 13:58:57 GMT Stefan Behnel wrote: > Barry Scott schrieb am 10.02.19 um 13:08: > > After calling PyObject_GetAttrString() I expected to get a PyObject string > > back but I found that I had been given a <getset_description> instead. > > > > (gdb) p *args_o > > $4 = <getset_descriptor at remote 0x7fffea87c7e0> > > > > What is going on and how do I get from the <getset_descriptor> to the > > object I want? > > Phil is right about the function itself, but my guess is that you called > GetAttr() on a class instead of an instance. Read up on Python descriptors > to understand what difference that makes. > > https://docs.python.org/3/howto/descriptor.html > > Basically, you got something like a property object back, but not the value > that the property maintaines. If you look up the attribute on the instance, > the property (or descriptor) will hand it to you. The same applies to > method lookups and other special attributes that may also be implemented as > descriptors.
Thanks that the clue I needed. I had assumed that PyErr_Occurred() returned the instance, but it returns the type and as you explained that gives you the get_set_descriptor. I need to use PyErr_Fetch to get the instance. > Also take a look at Cython, which is designed to keep users from having to > learn all these things and instead lets you do them in Python. > > https://cython.org/ I'm adding better code to look at exceptions to PyCXX and hit this issue. Barry PyCXX maintainer. -- https://mail.python.org/mailman/listinfo/python-list
