[英]cmake finds wrong python libs
我是CMake的新手,无法理解一些使用概念。
我正在从c ++程序调用python脚本:
#include <Python.h>
...
Py_Initialize();
PyRun_SimpleFile(...);
Py_Finalize();
我的cmake文件中相应的cmake条目是:
FIND_PACKAGE(PythonLibs REQUIRED)
...
TARGET_LINK_LIBRARIES(MyApplication ${PYTHON_LIBRARIES})
只要我的python脚本没有使用安装在site-packages目录中的任何模块,这就可以工作,否则我会得到一个ImportError。 这个问题展示了如何使用CMake查找site-packages目录的位置,但是我应该告诉CMake如何处理呢?
编辑:问题解决了。 事实证明,FIND_PACKAGE(PythonLibs)从我正常使用的版本中找到了不同的python安装(/usr/local/lib/libpython2.7.dylib而不是/Library/Frameworks/Python.framework/Versions/2.7/lib/libpython2。 7.dylib - 我在Mac上),这是我如何获得标准的python模块,但没有我自己安装。 为了将PYTHONPATH改回正常,我补充道
try:
import some_package
except ImportError:
if "my_python_path" in sys.path: raise
sys.path.append("my_python_path")
在我的python脚本的顶部。
解决找到错误版本的问题的最佳方法(例如3.0而不是2.7)是指定find_package的最小版本(这将选择任何版本> = 2.7):
FIND_PACKAGE(PythonLibs 2.7 REQUIRED)
或者获得确切的版本:
FIND_PACKAGE(PythonLibs 2.7.5 EXACT REQUIRED)
您可以通过指定python库的路径告诉cmake在哪里找到这个PythonLibs,如下所示:
cmake -DPYTHON_LIBRARIES=/Library/Frameworks/Python.framework/Versions/2.7/lib/libpython2.7.dylib .
然后,这会将cmake中的$ {PYTHON_LIBRARIES}设置为正确的路径。
要找出哪些其他可能的选项(除了PYTHON_LIBRARIES)你可以给cmake(使用-DARG选项)尝试运行
ccmake .
然后按c
配置,按t
选择高级选项。
例如,您可能还想设置
-DPYTHON_LIBRARY='/softwarepath/Python/Python2.7/lib/libpython2.7.so'
-DPYTHON_INCLUDE='/softwarepath/Python/Python2.7/include'
您可以在cmake libs \\usr\\share\\cmake-3.2.3\\Modules\\FindPythonLibs.cmake
:
set(PYTHON_LIBRARY "\\usr\\lib\\python2.7")
set(PYTHON_INCLUDE_DIR "\\usr\\include\\python2.7")
当你这样做时,你实际上是在程序中嵌入python。 你有没有在PyRun_SimpleFile之前调用Py_Initialize()? 看看在另一个应用程序中嵌入Python 。
Py_Initialize()将设置sys.path并且需要设置python环境。
如果你能找到python的安装位置,可以设置python home来覆盖python路径计算。 在Py_Initialize()之前使用Py_SetPythonHome()。
在posix类型的操作系统上,这里是getpath.c中的注释(路径解析的cpython实现):
/* Search in some common locations for the associated Python libraries.
*
* Two directories must be found, the platform independent directory
* (prefix), containing the common .py and .pyc files, and the platform
* dependent directory (exec_prefix), containing the shared library
* modules. Note that prefix and exec_prefix can be the same directory,
* but for some installations, they are different.
*
* Py_GetPath() carries out separate searches for prefix and exec_prefix.
* Each search tries a number of different locations until a ``landmark''
* file or directory is found. If no prefix or exec_prefix is found, a
* warning message is issued and the preprocessor defined PREFIX and
* EXEC_PREFIX are used (even though they will not work); python carries on
* as best as is possible, but most imports will fail.
*
* Before any searches are done, the location of the executable is
* determined. If argv[0] has one or more slashes in it, it is used
* unchanged. Otherwise, it must have been invoked from the shell's path,
* so we search $PATH for the named executable and use that. If the
* executable was not found on $PATH (or there was no $PATH environment
* variable), the original argv[0] string is used.
*
* Next, the executable location is examined to see if it is a symbolic
* link. If so, the link is chased (correctly interpreting a relative
* pathname if one is found) and the directory of the link target is used.
*
* Finally, argv0_path is set to the directory containing the executable
* (i.e. the last component is stripped).
*
* With argv0_path in hand, we perform a number of steps. The same steps
* are performed for prefix and for exec_prefix, but with a different
* landmark.
*
* Step 1. Are we running python out of the build directory? This is
* checked by looking for a different kind of landmark relative to
* argv0_path. For prefix, the landmark's path is derived from the VPATH
* preprocessor variable (taking into account that its value is almost, but
* not quite, what we need). For exec_prefix, the landmark is
* Modules/Setup. If the landmark is found, we're done.
*
* For the remaining steps, the prefix landmark will always be
* lib/python$VERSION/os.py and the exec_prefix will always be
* lib/python$VERSION/lib-dynload, where $VERSION is Python's version
* number as supplied by the Makefile. Note that this means that no more
* build directory checking is performed; if the first step did not find
* the landmarks, the assumption is that python is running from an
* installed setup.
*
* Step 2. See if the $PYTHONHOME environment variable points to the
* installed location of the Python libraries. If $PYTHONHOME is set, then
* it points to prefix and exec_prefix. $PYTHONHOME can be a single
* directory, which is used for both, or the prefix and exec_prefix
* directories separated by a colon.
*
* Step 3. Try to find prefix and exec_prefix relative to argv0_path,
* backtracking up the path until it is exhausted. This is the most common
* step to succeed. Note that if prefix and exec_prefix are different,
* exec_prefix is more likely to be found; however if exec_prefix is a
* subdirectory of prefix, both will be found.
*
* Step 4. Search the directories pointed to by the preprocessor variables
* PREFIX and EXEC_PREFIX. These are supplied by the Makefile but can be
* passed in as options to the configure script.
*
* That's it!
*
* Well, almost. Once we have determined prefix and exec_prefix, the
* preprocessor variable PYTHONPATH is used to construct a path. Each
* relative path on PYTHONPATH is prefixed with prefix. Then the directory
* containing the shared library modules is appended. The environment
* variable $PYTHONPATH is inserted in front of it all. Finally, the
* prefix and exec_prefix globals are tweaked so they reflect the values
* expected by other code, by stripping the "lib/python$VERSION/..." stuff
* off. If either points to the build directory, the globals are reset to
* the corresponding preprocessor variables (so sys.prefix will reflect the
* installation location, even though sys.path points into the build
* directory). This seems to make more sense given that currently the only
* known use of sys.prefix and sys.exec_prefix is for the ILU installation
* process to find the installed Python tree.
*/
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