c++ - 为 Python 3 与 Python 2 编写包装器

Question

在 Python 中，如果一个人的目标是使其与 Py3 和 Py2 兼容，那么为 C++ 库编写 Python 包装器的方式有什么不同吗？

或者最初为 Py2 编写的包装器是否应该以与 Py3 相同的方式工作，反之亦然？据我了解，Python 包装器是用 c++ 编写的 .cxx 文件，然后必须对其进行编译。

详情

我问是因为我想安装 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(Windows 7 32 位，通过“PATH= C:/Python27[or Python34]”和“python setup.py install”在命令行中)。我的希望是为 Python 3 恢复这个惊人的包装器模块，并希望这里的其他任何人都能提供帮助。

我可以在 Python 2.6 和 2.7 上毫无问题地编译它，而且我同时拥有 Visual C++ 2008 和 2010，所以这不是编译器问题。问题似乎出在实际的 .cxx 包装器代码中。

会不会是 Aggdraw 包装器只考虑了 Python 2x(大约 10 年前)，所以它没有考虑 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分，如果有人可以帮助我确定有问题的部分是什么(请参阅下面的命令行错误代码)？如果我们修复了它，那么我将使用指向“恢复的”包装代码的链接来更新这篇文章。

如果 Python 2 和 3 包装器之间应该没有区别，那么知道为什么我在 Py3 而不是 Py2 中得到下面的错误代码吗？

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 python 版本之间都有变化。您可以浏览更改列表并查看到底有什么不同以及它不起作用的原因。

例如，ssizet 和 strings 在两个 Python 版本之间是不同的。

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