Python源码学习之PyType_Type和PyBaseObject_Type详解

PyTypeObject PyFloat_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "float",
    sizeof(PyFloatObject),
    0,
    (destructor)float_dealloc,                  

    // ...
    (reprfunc)float_repr,                       

    // ...
};

>>> float.__class__
<class 'type'>

>>> class Foo(object):
...     pass
...
>>> Foo.__class__
<class 'type'>

PyTypeObject PyType_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "type",                                     
    sizeof(PyHeapTypeObject),                   
    sizeof(PyMemberDef),                        
    (destructor)type_dealloc,                   

    // ...
    (reprfunc)type_repr,                        

    // ...
};

>>> type.__class__
<class 'type'>
>>> type.__class__ is type
True

0,                                          

if (PyType_Ready(&PyFloat_Type) < 0)
    Py_FatalError("Can't initialize float type");

int
PyType_Ready(PyTypeObject *type)
{
    // ...

    base = type->tp_base;
    if (base == NULL && type != &PyBaseObject_Type) {
        base = type->tp_base = &PyBaseObject_Type;
        Py_INCREF(base);
    }

    // ...
}

PyTypeObject PyBaseObject_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "object",                                   
    sizeof(PyObject),                           
    0,                                          
    object_dealloc,                             

    // ...
    object_repr,                                
};

>>> object.__class__
<class 'type'>

>>> print(object.__base__)
None