在任何地方,我都可以很容易地找到一个使用 Python C Extensions 编写方法的示例。并在 Python 中使用它。喜欢这个:Python 3 extension example
$ python3
>>> import hello
>>> hello.hello_world()
Hello, world!
>>> hello.hello('world')
Hello, world!
如何编写一个 hello word 功能齐全的 Python 类(不仅仅是一个模块方法)?
我认为这是 How to wrap a C++ object using pure Python Extension API (python3)?问题有一个例子,但它似乎并不是最小的,因为他正在使用(或包装?)C++ 类。
例如:
class ClassName(object):
"""docstring for ClassName"""
def __init__(self, hello):
super().__init__()
self.hello = hello
def talk(self, world):
print( '%s %s' % ( self.hello, world ) )
这个带有 C 扩展的 Python 类示例的等价物是什么?
我会这样使用它:
from .mycextensionsmodule import ClassName
classname = ClassName("Hello")
classname.talk( 'world!' )
# prints "Hello world!"
我的目标是编写一个完全用 C 语言编写的类以提高性能(我项目中的所有其他类都将使用 Python,除了这个)。我不是在寻找使用 ctypes 的可移植性, 两个黑框都没有使用 Boost.Python或 SWIG .只是一个纯粹用 Python C 扩展编写的高性能类。
在我得到这个
Hello word
之后工作时,我可以在 Python Extensive 文档中找到自己的答案:最佳答案
另见:Python instance method in C
创建名为 MANIFEST.in
的文件
include README.md
include LICENSE.txt
recursive-include source *.h
创建名为 setup.py
的文件#!/usr/bin/env python3
# -*- coding: UTF-8 -*-
from setuptools import setup, Extension
__version__ = '0.1.0'
setup(
name = 'custom',
version = __version__,
package_data = {
'': [ '**.txt', '**.md', '**.py', '**.h', '**.hpp', '**.c', '**.cpp' ],
},
ext_modules = [
Extension(
name = 'custom',
sources = [
'source/custom.cpp',
],
include_dirs = ['source'],
)
],
)
创建名为 source/custom.cpp
的文件#define PY_SSIZE_T_CLEAN
#include <Python.h>
#include "structmember.h"
typedef struct {
PyObject_HEAD
PyObject *first; /* first name */
PyObject *last; /* last name */
int number;
} CustomObject;
static int
Custom_traverse(CustomObject *self, visitproc visit, void *arg)
{
Py_VISIT(self->first);
Py_VISIT(self->last);
return 0;
}
static int
Custom_clear(CustomObject *self)
{
Py_CLEAR(self->first);
Py_CLEAR(self->last);
return 0;
}
static void
Custom_dealloc(CustomObject *self)
{
PyObject_GC_UnTrack(self);
Custom_clear(self);
Py_TYPE(self)->tp_free((PyObject *) self);
}
static PyObject *
Custom_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
CustomObject *self;
self = (CustomObject *) type->tp_alloc(type, 0);
if (self != NULL) {
self->first = PyUnicode_FromString("");
if (self->first == NULL) {
Py_DECREF(self);
return NULL;
}
self->last = PyUnicode_FromString("");
if (self->last == NULL) {
Py_DECREF(self);
return NULL;
}
self->number = 0;
}
return (PyObject *) self;
}
static int
Custom_init(CustomObject *self, PyObject *args, PyObject *kwds)
{
static char *kwlist[] = {"first", "last", "number", NULL};
PyObject *first = NULL, *last = NULL, *tmp;
if (!PyArg_ParseTupleAndKeywords(args, kwds, "|UUi", kwlist,
&first, &last,
&self->number))
return -1;
if (first) {
tmp = self->first;
Py_INCREF(first);
self->first = first;
Py_DECREF(tmp);
}
if (last) {
tmp = self->last;
Py_INCREF(last);
self->last = last;
Py_DECREF(tmp);
}
return 0;
}
static PyMemberDef Custom_members[] = {
{"number", T_INT, offsetof(CustomObject, number), 0,
"custom number"},
{NULL} /* Sentinel */
};
static PyObject *
Custom_getfirst(CustomObject *self, void *closure)
{
Py_INCREF(self->first);
return self->first;
}
static int
Custom_setfirst(CustomObject *self, PyObject *value, void *closure)
{
if (value == NULL) {
PyErr_SetString(PyExc_TypeError, "Cannot delete the first attribute");
return -1;
}
if (!PyUnicode_Check(value)) {
PyErr_SetString(PyExc_TypeError,
"The first attribute value must be a string");
return -1;
}
Py_INCREF(value);
Py_CLEAR(self->first);
self->first = value;
return 0;
}
static PyObject *
Custom_getlast(CustomObject *self, void *closure)
{
Py_INCREF(self->last);
return self->last;
}
static int
Custom_setlast(CustomObject *self, PyObject *value, void *closure)
{
if (value == NULL) {
PyErr_SetString(PyExc_TypeError, "Cannot delete the last attribute");
return -1;
}
if (!PyUnicode_Check(value)) {
PyErr_SetString(PyExc_TypeError,
"The last attribute value must be a string");
return -1;
}
Py_INCREF(value);
Py_CLEAR(self->last);
self->last = value;
return 0;
}
static PyGetSetDef Custom_getsetters[] = {
{"first", (getter) Custom_getfirst, (setter) Custom_setfirst,
"first name", NULL},
{"last", (getter) Custom_getlast, (setter) Custom_setlast,
"last name", NULL},
{NULL} /* Sentinel */
};
static PyObject *
Custom_name(CustomObject *self, PyObject *Py_UNUSED(ignored))
{
return PyUnicode_FromFormat("%S %S", self->first, self->last);
}
static PyMethodDef Custom_methods[] = {
{"name", (PyCFunction) Custom_name, METH_NOARGS,
"Return the name, combining the first and last name"
},
{NULL} /* Sentinel */
};
static PyTypeObject CustomType = {
PyVarObject_HEAD_INIT(NULL, 0)
.tp_name = "custom.Custom",
.tp_doc = "Custom objects",
.tp_basicsize = sizeof(CustomObject),
.tp_itemsize = 0,
.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
.tp_new = Custom_new,
.tp_init = (initproc) Custom_init,
.tp_dealloc = (destructor) Custom_dealloc,
.tp_traverse = (traverseproc) Custom_traverse,
.tp_clear = (inquiry) Custom_clear,
.tp_members = Custom_members,
.tp_methods = Custom_methods,
.tp_getset = Custom_getsetters,
};
static PyModuleDef custommodule = {
PyModuleDef_HEAD_INIT,
.m_name = "custom",
.m_doc = "Example module that creates an extension type.",
.m_size = -1,
};
PyMODINIT_FUNC
PyInit_custom(void)
{
PyObject *m;
if (PyType_Ready(&CustomType) < 0)
return NULL;
m = PyModule_Create(&custommodule);
if (m == NULL)
return NULL;
Py_INCREF(&CustomType);
PyModule_AddObject(m, "Custom", (PyObject *) &CustomType);
return m;
}
然后,要编译并安装它,您可以运行:pip3 install . -v
python3 setup.py install
作为这个问题的旁注How to use setuptools packages and ext_modules with the same name?不要混在同一个项目上*.py
文件和 Python C 扩展,即仅使用纯 C/C++,构建 Python C 扩展而不添加 packages = [ 'package_name' ]
条目,因为它们导致 Python C 扩展代码运行 30%,即如果程序需要 7 秒才能运行,现在使用 *.py
文件,这将需要 11 秒。引用:
关于python - 具有 Python C 扩展的类(不是方法)的完整和最小示例?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/56203127/