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使用c擴充套件python

pyerr_*()函式是將乙個異常物件壓入到python直譯器的異常棧中

pyerr_clear()函式是將python異常棧中棧頂的元素彈出, 呼叫這個函式通常就相當於在python程式中的try: except: 語句中except的作用

python中的api, 每乙個模組對應的api是pymodname_funcinmod()

python擴充套件模組的函式模板:

// first

static pyobject *exfunc(pyobject *self, pyobject *args) is the symbol of the end of pymethoddef array, python interpretor will stop walking

this pymethoddef array when meeting it.

according to the official:

when using only meth_varargs, the function should expect the python-level parameters to be passed in as a tuple

acceptable for parsing via pyarg_parsetuple()

,// third

static struct pymoduledef exmodule = ",

"abc", 123, "def", 456)

py_buildvalue("((ii)(ii)) (ii)",

1, 2, 3, 4, 5, 6) (((1, 2), (3, 4)), (5, 6))

我們知道python知道用特定的py_init, 他是如何實現的呢, 其實使用了巨集中的#, 在巨集定義中，使用 # 將引數轉為字串

如果是借來的引用的話, 是不會增加該物件的引用計數的, 但是在借來的基礎上, 使用py_increase增加它的引用計數, 可以把借來的轉為自己持有的

幾乎所有的python建立pyobject物件的api都會返回乙個擁有的引用, 同時大多數的從乙個物件中取出另乙個物件的函式api也都是擁有的引用, 例外的pytuple_getitem(), pylist_getitem(), pydict_getitem(), pyimport_addmodule() and pydict_getitemstring()等函式則是返回借來的物件

傳入引數到python的api中, 大多數的引數物件都是不會增加引用的, 但是pytuple_setitem() and pylist_setitem()是例外

對24和25的補充, 使用借來的引用, 它的存活週期是乙個pythoncfunction, 如果需要物件存起來的話, 就會調動py_increase增加引用計數, 但是如果要返回乙個python物件的話, 需要增加其引用計數

一般pythonapi不怎麼檢驗python物件為null的情況

模組的一些初始化操作在pyinit_函式中進行

如果希望新增新的內建型別, 這個我最熟悉(那是多麼痛的領悟), 因為我寫過, 定義乙個type型別結構體, 第乙個是pyobject_head, 接著在初始化type(一定要有.tp_flags = py_tpflags_default,), 在pyinit_中將該型別新增到模組物件中

在擴充套件模組中設定的名稱為modulename.subname

if (pytype_ready(&customtype) < 0)

return;

this adds the type to the module dictionary.

pymodule_addobject(m, "custom", (pyobject *) &customtype);

乙個完整的type賦值, 根據1, 2, 3得知, 為什麼每次建立乙個型別都會有new, init, del, 因為在其對應的pytypeobject中需要指明, 並且不是通過pymethoddef表控制的

static pytypeobject customtype = sublistobject;

static pyobject *

sublist_increment(sublistobject *self, pyobject *unused)

self->state++;

return pylong_fromlong(self->state);

static pymethoddef sublist_methods = ,

,static int

sublist_init(sublistobject *self, pyobject *args, pyobject *kwds)

if (pylist_type.tp_init((pyobject *) self, args, kwds) < 0)

return -1;

self->state = 0;

return 0;

static pytypeobject sublisttype = customobject;

static void

custom_dealloc(customobject *self)

py_xdecref(self->first);

py_xdecref(self->last);

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) ;

pyobject *first = null, *last = null, *tmp;

if (!pyarg_parsetupleandkeywords(args, kwds, "|uui", kwlist,

&first, &last,

&self->number))

return -1;

if (first) ,

/* 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)

pyobject *tmp;

if (value == 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 = /* sentinel */

static pytypeobject customtype = {

pyvarobject_head_init(null, 0)

.tp_name = "custom3.custom",

.tp_doc = "custom objects",

.tp_basicsize = sizeof(customobject),

.tp_itemsize = 0,

.tp_flags = py_tpflags_default | py_tpflags_basetype,

.tp_new = custom_new,

.tp_init = (initproc) custom_init,

.tp_dealloc = (destructor) custom_dealloc,

.tp_members = custom_members,

.tp_methods = custom_methods,

.tp_getset = custom_getsetters,

static pymoduledef custommodule = {

pymoduledef_head_init,

.m_name = "custom3",

.m_doc = "example module that creates an extension type.",

.m_size = -1,

pymodinit_func

pyinit_custom3(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;

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