> On Sun, Jan 25, 2009 at 9:01 AM, Matthieu Brucher > <matthieu.brucher at gmail.com> wrote: > > 2009/1/25 Luke Kenneth Casson Leighton <lkcl at lkcl.net>: > >> according to the wikipedia entry on dlls, dlls do not support data, > >> only functions. > > > > What do you mean by "not support data"? Having global data variables in a > > dll? > > In wikipedia, it is explicitely told that this is possible to have > > data (http://en.wikipedia.org/wiki/Dynamic-link_library). Without > > them, shared library cannot be used.
matthieu, thank you for responding. from http://en.wikipedia.org/wiki/Dynamic-link_library: "Third, dynamic linking is inherently the wrong model for paged memory managed systems. Such systems work best with the idea that code is invariant from the time of assembly/compilation on. ........... Data references do not need to be so vectored because DLLs do not share data." ^^^^^^^^^^^^^^^^^^^^ does anyone happen to know what this means? also, what do you mean by "without data, shared library cannot be used"? you can _always_ call a function which returns a pointer to the data, rather than access the data directly. > Indeed. That's why the header files contain > define PyAPI_DATA(RTYPE) extern __declspec(dllexport) RTYPE > define PyAPI_DATA(RTYPE) extern __declspec(dllimport) RTYPE curt, thank you for responding. i'd seen this: i understood it - and... yet... mingw happily segfaults when asked to access _any_ data in _any_ object file of the python2N dll. Py_NoneStruct, PyExc_* (of which there are about 50), Py*_Type - all of them. solutions so far involve ensuring that anything declared with PyAPI_DATA is *NEVER* accessed [across a dll boundary] - by for example moving the module into python2N.dll. also, yes i had looked up how to do .def files, and how __declspec(dllexport) etc. work. of all the examples that you find about dlltool, mingw, dlls, defs, etc. they _all_ say "function." to declare a _function_ you do X, Y and Z. not one of them says "to place data in a dll, you do X Y and Z". then, looking at the wine dlls and .defs, i haven't yet found a _single_ one which returns data - they're _all_ functions (from looking so far. e.g. i expected MSVCRT.DLL errno to be an int - it's not: it's a function). *sigh*. if this turns out to be yet another gcc / mingw bug i'm going to be slightly annoyed. only slightly, because this _is_ free software, after all :) l. _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
