python的type class

在python中，用户定义的class是一个PyTypeObject （ XXX_Type）对象。

#PyType_Type是一切类的基类，这是一个全局数据
PyTypeObject PyType_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "type",                                     /* tp_name */
    sizeof(PyHeapTypeObject),                   /* tp_basicsize */
    sizeof(PyMemberDef),                        /* tp_itemsize */
    (destructor)type_dealloc,                   /* tp_dealloc */
    0,                                          /* tp_print */
    0,                                          /* tp_getattr */
    0,                                          /* tp_setattr */
    0,                                  /* tp_compare */
    (reprfunc)type_repr,                        /* tp_repr */
    0,                                          /* tp_as_number */
    0,                                          /* tp_as_sequence */
    0,                                          /* tp_as_mapping */
    (hashfunc)_Py_HashPointer,                  /* tp_hash */
    (ternaryfunc)type_call,                     /* tp_call */
    0,                                          /* tp_str */
    (getattrofunc)type_getattro,                /* tp_getattro */
    (setattrofunc)type_setattro,                /* tp_setattro */
    0,                                          /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
        Py_TPFLAGS_BASETYPE | Py_TPFLAGS_TYPE_SUBCLASS,         /* tp_flags */
    type_doc,                                   /* tp_doc */
    (traverseproc)type_traverse,                /* tp_traverse */
    (inquiry)type_clear,                        /* tp_clear */
    type_richcompare,                                           /* tp_richcompare */
    offsetof(PyTypeObject, tp_weaklist),        /* tp_weaklistoffset */
    0,                                          /* tp_iter */
    0,                                          /* tp_iternext */
    type_methods,                               /* tp_methods */
    type_members,                               /* tp_members */
    type_getsets,                               /* tp_getset */
    0,                                          /* tp_base */
    0,                                          /* tp_dict */
    0,                                          /* tp_descr_get */
    0,                                          /* tp_descr_set */
    offsetof(PyTypeObject, tp_dict),            /* tp_dictoffset */
    type_init,                                  /* tp_init */
    0,                                          /* tp_alloc */
    type_new,                                   /* tp_new */
    PyObject_GC_Del,                            /* tp_free */
    (inquiry)type_is_gc,                        /* tp_is_gc */
};

list是一个具体的type：

PyTypeObject PyList_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "list",
    sizeof(PyListObject),
    0,
    (destructor)list_dealloc,                   /* tp_dealloc */
    (printfunc)list_print,                      /* tp_print */
    0,                                          /* tp_getattr */
    0,                                          /* tp_setattr */
    0,                                          /* tp_compare */
    (reprfunc)list_repr,                        /* tp_repr */
    0,                                          /* tp_as_number */
    &list_as_sequence,                          /* tp_as_sequence */
    &list_as_mapping,                           /* tp_as_mapping */
    (hashfunc)PyObject_HashNotImplemented,      /* tp_hash */
    0,                                          /* tp_call */
    0,                                          /* tp_str */
    PyObject_GenericGetAttr,                    /* tp_getattro */
    0,                                          /* tp_setattro */
    0,                                          /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
        Py_TPFLAGS_BASETYPE | Py_TPFLAGS_LIST_SUBCLASS,         /* tp_flags */
    list_doc,                                   /* tp_doc */
    (traverseproc)list_traverse,                /* tp_traverse */
    (inquiry)list_clear,                        /* tp_clear */
    list_richcompare,                           /* tp_richcompare */
    0,                                          /* tp_weaklistoffset */
    list_iter,                                  /* tp_iter */
    0,                                          /* tp_iternext */
    list_methods,                               /* tp_methods */
    0,                                          /* tp_members */
    0,                                          /* tp_getset */
    0,                                          /* tp_base */
    0,                                          /* tp_dict */
    0,                                          /* tp_descr_get */
    0,                                          /* tp_descr_set */
    0,                                          /* tp_dictoffset */
    (initproc)list_init,                        /* tp_init */
    PyType_GenericAlloc,                        /* tp_alloc */
    PyType_GenericNew,                          /* tp_new */
    PyObject_GC_Del,                            /* tp_free */
};

typedef struct {
    PyObject_VAR_HEAD
    /* Vector of pointers to list elements.  list[0] is ob_item[0], etc. */
    PyObject **ob_item;

    /* ob_item contains space for 'allocated' elements.  The number
     * currently in use is ob_size.
     * Invariants:
     *     0 <= ob_size <= allocated
     *     len(list) == ob_size
     *     ob_item == NULL implies ob_size == allocated == 0
     * list.sort() temporarily sets allocated to -1 to detect mutations.
     *
     * Items must normally not be NULL, except during construction when
     * the list is not yet visible outside the function that builds it.
     */
    Py_ssize_t allocated;
} PyListObject;

list的实例对象是PyListObject，保存了list的数据，由list对象的head可以知道他的PyList_Type，从而可以调用PyList_Type的方法。

PyTypeObject PyDict_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "dict",
    sizeof(PyDictObject),
    0,
    (destructor)dict_dealloc,                   /* tp_dealloc */
    (printfunc)dict_print,                      /* tp_print */
    0,                                          /* tp_getattr */
    0,                                          /* tp_setattr */
    (cmpfunc)dict_compare,                      /* tp_compare */
    (reprfunc)dict_repr,                        /* tp_repr */
    0,                                          /* tp_as_number */
    &dict_as_sequence,                          /* tp_as_sequence */
    &dict_as_mapping,                           /* tp_as_mapping */
    (hashfunc)PyObject_HashNotImplemented,      /* tp_hash */
    0,                                          /* tp_call */
    0,                                          /* tp_str */
    PyObject_GenericGetAttr,                    /* tp_getattro */
    0,                                          /* tp_setattro */
    0,                                          /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
        Py_TPFLAGS_BASETYPE | Py_TPFLAGS_DICT_SUBCLASS,         /* tp_flags */
    dictionary_doc,                             /* tp_doc */
    dict_traverse,                              /* tp_traverse */
    dict_tp_clear,                              /* tp_clear */
    dict_richcompare,                           /* tp_richcompare */
    0,                                          /* tp_weaklistoffset */
    (getiterfunc)dict_iter,                     /* tp_iter */
    0,                                          /* tp_iternext */
    mapp_methods,                               /* tp_methods */
    0,                                          /* tp_members */
    0,                                          /* tp_getset */
    0,                                          /* tp_base */
    0,                                          /* tp_dict */
    0,                                          /* tp_descr_get */
    0,                                          /* tp_descr_set */
    0,                                          /* tp_dictoffset */
    dict_init,                                  /* tp_init */
    PyType_GenericAlloc,                        /* tp_alloc */
    dict_new,                                   /* tp_new */
    PyObject_GC_Del,                            /* tp_free */
};

PyTypeObject PyBaseObject_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "object",                                   /* tp_name */
    sizeof(PyObject),                           /* tp_basicsize */
    0,                                          /* tp_itemsize */
    object_dealloc,                             /* tp_dealloc */
    0,                                          /* tp_print */
    0,                                          /* tp_getattr */
    0,                                          /* tp_setattr */
    0,                                          /* tp_compare */
    object_repr,                                /* tp_repr */
    0,                                          /* tp_as_number */
    0,                                          /* tp_as_sequence */
    0,                                          /* tp_as_mapping */
    (hashfunc)_Py_HashPointer,                  /* tp_hash */
    0,                                          /* tp_call */
    object_str,                                 /* tp_str */
    PyObject_GenericGetAttr,                    /* tp_getattro */
    PyObject_GenericSetAttr,                    /* tp_setattro */
    0,                                          /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
    PyDoc_STR("The most base type"),            /* tp_doc */
    0,                                          /* tp_traverse */
    0,                                          /* tp_clear */
    0,                                          /* tp_richcompare */
    0,                                          /* tp_weaklistoffset */
    0,                                          /* tp_iter */
    0,                                          /* tp_iternext */
    object_methods,                             /* tp_methods */
    0,                                          /* tp_members */
    object_getsets,                             /* tp_getset */
    0,                                          /* tp_base */
    0,                                          /* tp_dict */
    0,                                          /* tp_descr_get */
    0,                                          /* tp_descr_set */
    0,                                          /* tp_dictoffset */
    object_init,                                /* tp_init */
    PyType_GenericAlloc,                        /* tp_alloc */
    object_new,                                 /* tp_new */
    PyObject_Del,                               /* tp_free */
};

o=object(),object也是一种类。tp_dict有什么作用？类的__dict__是用来保存实例对象的。

>>> class t(object):
    name='hai'
    age=41
    def __init__(self,a,b):
        self.m1=a
        self.m2=b
    def func2():
        pass

    
>>> oo=t(5,7)
>>> oo.__dict__
{'m1': 5, 'm2': 7}
>>> t.__dict__
dict_proxy({'func2': <function func2 at 0x013AF570>, '__module__': '__main__', 'name': 'hai', 'age': 41, '__dict__': <attribute '__dict__' of 't' objects>, '__weakref__': <attribute '__weakref__' of 't' objects>, '__doc__': None, '__init__': <function __init__ at 0x013AF530>})
>>> 

 

>>> class t(object):
    name='hai'
    age=41

    
>>> o=t()
>>> dir(o)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'age', 'name']
>>> o.__dict__
{}
>>> dir(t)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'age', 'name']
>>> type(t)
<type 'type'>
>>> o.__class__
<class '__main__.t'>
>>> t.__class__
<type 'type'>
>>> 
>>> class t(object):
    name='hai'
    age=41
    def func1():
        pass
    def func2():
        pass

    
>>> dir(t)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'age', 'func1', 'func2', 'name']
>>> o=t()
>>> dir(o)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'age', 'func1', 'func2', 'name']
>>>