Re: [Python-modules-team] Bug#643873: Making Numpy transition less painful
* Sandro Tosi <morph@debian.org>, 2011-10-31, 19:57:
Dependencies generated by dh_numpy
==================================
dh_numpy would generate dependency either on "python-numpy-abi$N" (by
default) or on "python-numpy-api$N" (if a special option, say,
--strict, is used).
I just realized that, in order to make packages using Cython happy, the
first one will have to be:
"python-numpy-abi$N, python-numpy (>= $V)"
where $V is the first version with the current API. [0]
The second option would be needed for packages which are overzealous
at checking ABI unless/until we fix them (we have at least one package
in the archive which does that).
[1]
do you think it's possible for the same source package to generate 2
binaries one needing python-numpy-abi$N and the other needing
python-numpy-api$N ?
It'd quite crazy, but in theory, yes, that could happen.
how would you imagine to handle this? with "dh_numpy -pbin1
--strict\ndh_numpy -pbin2"
Exactly.
Avoiding strict dependencies for arch:all packages
==================================================
dh_numpy should not generate any dependencies in arch:all packages.
Such packages cannot rely on Numpy ABI, and rebuilding them for
transition purposes is causes lot of trouble. (We already had to do
this in the past!) For the same reason,
/usr/share/python/dist/python-numpy needs to go away.
so just a python-numpy added to python:Depends?
I was rather thinking about not touching such packages at all. But
adding unversioned python-numpy to ${python:Depends} would work, too.
how does it fix with a source that generates an arch:all and an
arch:any (the latter using either -abi or -api)?
dh_numpy would generate different substitutions for each of them. I
don't see any problem here.
Gracefully handling the upcoming transition
-------------------------------------------
A number of packages in the archive already has dependency on
"python-numpy (<< 1:1.6)", which is not satisfiable by the package in
experimental. To avoid this transition (or at least reduce its size)
we could do one of two things:
1) Implement the proposed changes first in unstable, schedule binNMUs,
then upload Numpy 1.6 to unstable.
2) Implement the proposed changes only for Numpy 1.6, but make
dh_numpy generate alternative versioned dependencies:
"python-numpy (>= 1:1.5.1), python-numpy-abi$N | python-numpy (<< 1:1.6.2)".
Then upload Numpy 1.6, schedule binNMUs.
Mh, my lazy instinct would say 2) that has also the advantage to bring
1.6 into unstable (but I guess 1.7 is coming soon).
Yeah, that option sounded very appealing, but turned out not feasible
after all. See my comment about Cython at the top of this mail.
C_API_VERSION has been bumped from 4 to 6, so $V should be at least >=
1:1.6.
Please also note taht my perl foo is barely None, so I'd need some help
in extending dh_numpy :)
No problem, I can do the coding part once we agree how everything should
work. :)
[0] Cython generates this code for importing C types:
| if (!strict && ((PyTypeObject *)result)->tp_basicsize > (Py_ssize_t)size) {
| PyOS_snprintf(warning, sizeof(warning),
| "%s.%s size changed, may indicate binary incompatibility",
| module_name, class_name);
| #if PY_VERSION_HEX < 0x02050000
| if (PyErr_Warn(NULL, warning) < 0) goto bad;
| #else
| if (PyErr_WarnEx(NULL, warning, 0) < 0) goto bad;
| #endif
| }
| else if (((PyTypeObject *)result)->tp_basicsize != (Py_ssize_t)size) {
| PyErr_Format(PyExc_ValueError,
| "%s.%s has the wrong size, try recompiling",
| module_name, class_name);
| goto bad;
| }
That is, import will fail if the size imported type is shorter at
runtime that at build time.
[1] Pyrex (and very old versions of Cython) generates this code for
importing C types:
| if (((PyTypeObject *)result)->tp_basicsize != size) {
| PyErr_Format(PyExc_ValueError,
| "%s.%s does not appear to be the correct type object",
| module_name, class_name);
| goto bad;
So import will fail with exception if the size imported type is
different at runtime that at build time.
--
Jakub Wilk
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