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Separate compilation of time and datetime modules #53258
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Here is the history of the issue per Martin v. Löwis on python-dev: """ This was added with ------------------------------------------------------------------------ Add compilation of timemodule.c with datetimemodule.c to get ------------------------------------------------------------------------ So it's clearly intentional. I doubt its desirable, though. If only I hope this is non-controversial, but I would like someone to comment on the choice of file name. I chose _timefunc.c to make it more distinguishable from module file names. Ideally, however I would like to see this in either _time.h/_time.c pair (both in Module dir like _math.{c,h}) or in pytime.h/pytime.c (like pymath.{c,h}). Marking this as "resource usage" because the patch will result in smaller size of datetime module. |
Based on IRC discussion, here is a modified patch that places C code in _time.c and creates a stub for _time.h so that future shared definitions can go there. |
Added new Module/_time.h to the patch. |
Committed in r82034. |
Reopen: r82034 broke Windows build ------- |
Fixed by r82035. |
this breaks the build if the time and datetime extensions are built statically into the python interpreter. The build fails with a link error; adding the _time extension to Modules/Setup.dist @@ -160,6 +160,7 @@
#cmath cmathmodule.c _math.c # -lm # complex math library functions
#math mathmodule.c _math.c # -lm # math library functions, e.g. sin()
#_struct _struct.c # binary structure packing/unpacking
+#_time _time.c # # segregated code shared between time and datetime modules
#time timemodule.c # -lm # time operations and variables
#operator operator.c # operator.add() and similar goodies
#_weakref _weakref.c # basic weak reference support you get another link error: libpython3.2.a(config.o):(.data+0x58): undefined reference to `PyInit__time' because _time isn't a proper extension. raising the severity as this is a regression |
please find attached a patch to build as a statically linked extension, registering the empty _time module. |
_time.c is not supposed to be compiled into an extension. It is similar to _math.c - if you add a line _math _math.c to Setup, you get a similar compile error. What needs to be done, however, is to add _time.c to time and datetime lines. See issue9012a.diff. |
doesn't work: ranlib libpython3.2.a |
Matthias, does building both the math and cmath modules statically into the interpreter fail in a similar manner? |
yes, same issue with math/cmath. |
Thanks. Looks like we need a general solution to the problem of shared (non-module) dependencies in modules. So all that's needed is a way to stop _time.o showing up twice in MODOBJS in the Makefile, right? (For some reason, ranlib on OS X doesn't seem to have any problem with multiply-defined symbols; obviously Linux is different.) |
I am merging in the nosy list from bpo-9079 after we had a lengthy discussion there and on IRC about the best way to share code between stdlib extension modules. For the bpo-9079, we decided to bring the shared code into python core, but this cannot be a general solution. I still don't see any solution other than exposing C API via a capsule mechanism, but Antoine objected saying that capsule mechanism is for 3rd party modules and should not be used in stdlib. |
Added patch that replicates the change in r82035 for Visual Studio 2005 (VC8) builds. |
What about PC/VS7.1/pythoncore.vcproj? Is there some automation in place to keep the project files in sync? ISTM, all the info to generate these should be in setup.py. The patch looks good, but I am hesitant to commit changes that I cannot test. |
No, there's no automated way to keep "legacy" Windows toolchains in sync; short of adopting something like Scons or CMAKE (which I'm *not* suggesting) I don't think I've seen a trustworthy way of doing so. The PCBuild's "readme.txt" states: "You can find build directories for older versions of Visual Studio and Visual C++ in the PC directory. The legacy build directories are no longer actively maintained and may not work out of the box." To date, I believe that the attitude toward these older build files has been "unsupported; use at own risk; patches welcome". |
On Wed, Jul 21, 2010 at 3:58 PM, Tim Lesher <report@bugs.python.org> wrote:
OK, I guess there is little risk in committing this patch. I'll do it |
Bump. This bug has priority high and it sounds like the patch is ready for commit. |
there are two pending patches here: time.diff - a hack that makes _time.c look like a module while it is not. add_time_to_vc8_build.diff - a patch for VC 8.0 project file. I don't like time.diff because it fixes the symptom rather than the core problem. I believe the code that is shared between C modules should be segregated into a true module which would expose its C API via capsule mechanism. Others suggested that this is an overkill and that capsule mechanism is not suitable for the stdlib. On the latter argument, I would like to point that unicodedata already uses capsule mechanism to make itself available to Python's builtin str type. As I mentioned in msg109219, this situation is not unique to time/datetime. The math and cmath modules similarly use linker tricks to share code in _math.c. Unassigning because I don't have an informed opinion on add_time_to_vc8_build.diff and cannot move the _time.c issue forward until similar problem is solved for _math.c which I used as the basis for _time.c design. |
msg111078 refers to r82035 for Visual Studio 2005 (VC8) builds. Given that http://code.activestate.com/lists/python-dev/131023/ refers to VC14 for 3.5 can we close this as out of date? |
No. The problem has nothing to do with the VS version. |
@Steve/Zach any interest in this one? |
This issue has been superseded by bpo-14180. __PyTime_DoubleToTimet no longer exists; its successor now lives in pytime.c. |
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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