详细

Question

在Python中，如果有人为Py3与Py2兼容，那么如何为c ++库编写Python包装器有什么不同？

或者，最初为Py2编写的包装器是否应该以相同的方式为Py3工作，反之亦然？据我所知，Python包装器是用c ++编写的.cxx文件，然后必须编译。

详细

我问，因为我想安装Aggdraw（c ++ Anti Grain Geometry绘图库的包装器），它在Python 2.6-7中工作，但在Python 3.4上导致错误（Windows 7 32位，通过“PATH = C：/ Python27 [或Python34]“和命令行中的”python setup.py install“。我希望能够为Python 3恢复这个令人惊叹的包装器模块，并且希望其他任何人都能在帮助方面感兴趣。

我可以在Python 2.6和2.7上编译它没有任何问题，我同时拥有Visual C ++ 2008和2010，因此它不是编译器问题。问题似乎是在实际的.cxx包装器代码中。

可能是Aggdraw包装器只是用Python 2x编写（大约10年前），所以它没有考虑到Python 3x中可能出现的问题？我最好的猜测是，由于版本3.4中已弃用和更改的功能，包装器无法将某些c ++对象/类型转换为Python。

我可能愿意通过.cxx包装器代码来更改必要的部件，如果有人可以帮我确定故障部件是什么（请参阅下面的命令行错误代码）？如果我们修复它，那么我将使用“复活的”包装代码的链接更新这篇文章。

如果Python 2和3包装器之间没有区别，那么为什么我在Py3中得到错误代码而不是Py2呢？

谢谢！

原始包装代码：click here

C:\Users\BIGKIMO\Desktop\aggdraw-master>python setup.py build
=== freetype not available (edit setup.py to enable)
running install
running build
running build_ext
building 'aggdraw' extension
C:\Program Files\Microsoft Visual Studio 10.0\VC\BIN\cl.exe /c /nologo /Ox /MD /
W3 /GS- /DNDEBUG -Iagg2/include -IC:\Python34\include -IC:\Python34\include /Tpa
ggdraw.cxx /Fobuild\temp.win32-3.4\Release\aggdraw.obj
aggdraw.cxx
aggdraw.cxx(124) : error C2440: 'initializing' : cannot convert from 'const char
 [5]' to 'Py_ssize_t'
        There is no context in which this conversion is possible
aggdraw.cxx(126) : error C2440: 'initializing' : cannot convert from 'destructor
' to 'printfunc'
        This conversion requires a reinterpret_cast, a C-style cast or function-
style cast
aggdraw.cxx(128) : error C2440: 'initializing' : cannot convert from 'getattrfun
c' to 'setattrfunc'
        This conversion requires a reinterpret_cast, a C-style cast or function-
style cast
aggdraw.cxx(142) : error C2440: 'initializing' : cannot convert from 'const char
 [4]' to 'Py_ssize_t'
        There is no context in which this conversion is possible
aggdraw.cxx(144) : error C2440: 'initializing' : cannot convert from 'destructor
' to 'printfunc'
        This conversion requires a reinterpret_cast, a C-style cast or function-
style cast
aggdraw.cxx(161) : error C2440: 'initializing' : cannot convert from 'const char
 [6]' to 'Py_ssize_t'
        There is no context in which this conversion is possible
aggdraw.cxx(163) : error C2440: 'initializing' : cannot convert from 'destructor
' to 'printfunc'
        This conversion requires a reinterpret_cast, a C-style cast or function-
style cast
aggdraw.cxx(187) : error C2440: 'initializing' : cannot convert from 'const char
 [5]' to 'Py_ssize_t'
        There is no context in which this conversion is possible
aggdraw.cxx(189) : error C2440: 'initializing' : cannot convert from 'destructor
' to 'printfunc'
        This conversion requires a reinterpret_cast, a C-style cast or function-
style cast
aggdraw.cxx(191) : error C2440: 'initializing' : cannot convert from 'getattrfun
c' to 'setattrfunc'
        This conversion requires a reinterpret_cast, a C-style cast or function-
style cast
aggdraw.cxx(207) : error C2440: 'initializing' : cannot convert from 'const char
 [5]' to 'Py_ssize_t'
        There is no context in which this conversion is possible
aggdraw.cxx(209) : error C2440: 'initializing' : cannot convert from 'destructor
' to 'printfunc'
        This conversion requires a reinterpret_cast, a C-style cast or function-
style cast
aggdraw.cxx(211) : error C2440: 'initializing' : cannot convert from 'getattrfun
c' to 'setattrfunc'
        This conversion requires a reinterpret_cast, a C-style cast or function-
style cast
aggdraw.cxx(488) : error C3861: 'PyString_Check': identifier not found
aggdraw.cxx(489) : error C3861: 'PyString_AS_STRING': identifier not found
aggdraw.cxx(575) : error C3861: 'PyString_Check': identifier not found
aggdraw.cxx(583) : error C3861: 'PyString_AS_STRING': identifier not found
aggdraw.cxx(584) : error C3861: 'PyString_GET_SIZE': identifier not found
aggdraw.cxx(730) : error C3861: 'PyInt_Check': identifier not found
aggdraw.cxx(730) : error C3861: 'PyInt_AS_LONG': identifier not found
aggdraw.cxx(731) : error C3861: 'PyInt_Check': identifier not found
aggdraw.cxx(731) : error C3861: 'PyInt_AS_LONG': identifier not found
aggdraw.cxx(735) : error C3861: 'PyInt_Check': identifier not found
aggdraw.cxx(735) : error C3861: 'PyInt_AS_LONG': identifier not found
aggdraw.cxx(736) : error C3861: 'PyInt_Check': identifier not found
aggdraw.cxx(736) : error C3861: 'PyInt_AS_LONG': identifier not found
aggdraw.cxx(742) : error C3861: 'PyInt_Check': identifier not found
aggdraw.cxx(742) : error C3861: 'PyInt_AS_LONG': identifier not found
aggdraw.cxx(745) : error C3861: 'PyInt_Check': identifier not found
aggdraw.cxx(745) : error C3861: 'PyInt_AS_LONG': identifier not found
aggdraw.cxx(759) : error C3861: 'PyInt_Check': identifier not found
aggdraw.cxx(760) : error C3861: 'PyInt_AsLong': identifier not found
aggdraw.cxx(763) : error C3861: 'PyString_Check': identifier not found
aggdraw.cxx(765) : error C3861: 'PyString_AS_STRING': identifier not found
aggdraw.cxx(788) : error C3861: 'PyString_Check': identifier not found
aggdraw.cxx(789) : error C3861: 'PyString_AS_STRING': identifier not found
aggdraw.cxx(1157) : error C3861: 'PyString_FromStringAndSize': identifier not fo
und
aggdraw.cxx(1289) : error C3861: 'PyString_FromString': identifier not found
aggdraw.cxx(1294) : error C3861: 'Py_FindMethod': identifier not found
aggdraw.cxx(1482) : error C3861: 'Py_FindMethod': identifier not found
aggdraw.cxx(1890) : error C3861: 'Py_FindMethod': identifier not found
aggdraw.cxx(1910) : error C3646: 'initaggdraw' : unknown override specifier
aggdraw.cxx(1911) : error C2091: function returns function
aggdraw.cxx(1911) : error C4430: missing type specifier - int assumed. Note: C++
 does not support default-int
aggdraw.cxx(1912) : error C2039: 'ob_type' : is not a member of '_typeobject'
        c:\python34\include\object.h(334) : see declaration of '_typeobject'
aggdraw.cxx(1912) : error C2039: 'ob_type' : is not a member of '_typeobject'
        c:\python34\include\object.h(334) : see declaration of '_typeobject'
aggdraw.cxx(1913) : error C2039: 'ob_type' : is not a member of '_typeobject'
        c:\python34\include\object.h(334) : see declaration of '_typeobject'
aggdraw.cxx(1913) : error C2039: 'ob_type' : is not a member of '_typeobject'
        c:\python34\include\object.h(334) : see declaration of '_typeobject'
aggdraw.cxx(1913) : error C2039: 'ob_type' : is not a member of '_typeobject'
        c:\python34\include\object.h(334) : see declaration of '_typeobject'
aggdraw.cxx(1915) : error C3861: 'Py_InitModule': identifier not found
aggdraw.cxx(1940) : warning C4508: 'DL_EXPORT' : function should return a value;
 'void' return type assumed

Answer 1

Python FFI库（ctype）在每个版本的python之间都有变化。您需要查看更改列表，看看究竟有什么不同以及它为什么不起作用。

例如，两个Python版本之间的ssizet和字符串不同。

https://docs.python.org/3/whatsnew/3.2.html#ctypes Differences in ctypes between Python 2 and 3

Answer 2

为了扩展前面的答案，有许多函数在Py2.7中对字符串起作用，现在对Py3中的字节或unicode起作用。同样，提到int的内容现在可能指的是long。正如这里引起问题的一个例子，pyBy_seck已经弃用了pyString_Check。请阅读以下内容以获取更多详细信息：

https://docs.python.org/3/howto/cporting.html?highlight=pystring

为Python 3和Python 2编写包装器

详细

2 个答案: