Python 原理笔记

typedef struct _object {
    _PyObject_HEAD_EXTRA
    Py_ssize_t ob_refcnt;       /* 引用计数，用于垃圾收集 */
    struct _typeobject *ob_type; /* 对象类型 */
} PyObject;

typedef struct {
    PyObject_VAR_HEAD
    PyObject **ob_item;
    Py_ssize_t allocated;
} PyListObject;

#define PyObject_VAR_HEAD      PyVarObject ob_base;

typedef struct {
    PyObject ob_base;
    Py_ssize_t ob_size; /* Number of items in variable part */
} PyVarObject;

/* file: Python/ceval.c */

PyObject *
_PyEval_EvalCodeWithName(PyObject *_co, PyObject *globals, PyObject *locals,
           PyObject *const *args, Py_ssize_t argcount,
           PyObject *const *kwnames, PyObject *const *kwargs,
           Py_ssize_t kwcount, int kwstep,
           PyObject *const *defs, Py_ssize_t defcount,
           PyObject *kwdefs, PyObject *closure,
           PyObject *name, PyObject *qualname)
{
    PyCodeObject* co = (PyCodeObject*)_co;
    PyFrameObject *f;
    PyObject *retval = NULL;
    PyObject **fastlocals, **freevars;
    PyThreadState *tstate;
    PyObject *x, *u;
    const Py_ssize_t total_args = co->co_argcount + co->co_kwonlyargcount;
    Py_ssize_t i, n;
    PyObject *kwdict;

    if (globals == NULL) {
        PyErr_SetString(PyExc_SystemError,
                        "PyEval_EvalCodeEx: NULL globals");
        return NULL;
    }

    /* Create the frame */
    tstate = PyThreadState_GET();
    assert(tstate != NULL);
    /* 创建新的栈帧 */
    f = _PyFrame_New_NoTrack(tstate, co, globals, locals);
    if (f == NULL) {
        return NULL;
    }
    fastlocals = f->f_localsplus;
    freevars = f->f_localsplus + co->co_nlocals;

    /* Create a dictionary for keyword parameters (**kwags) */
    if (co->co_flags & CO_VARKEYWORDS) {
        kwdict = PyDict_New();
        if (kwdict == NULL)
            goto fail;
        i = total_args;
        if (co->co_flags & CO_VARARGS) {
            i++;
        }
        SETLOCAL(i, kwdict);
    }
    else {
        kwdict = NULL;
    }

    /* Copy positional arguments into local variables */
    if (argcount > co->co_argcount) {
        n = co->co_argcount;
    }
    else {
        n = argcount;
    }
    for (i = 0; i < n; i++) {
        x = args[i];
        Py_INCREF(x);
        SETLOCAL(i, x);
    }

    /* Pack other positional arguments into the *args argument */
    if (co->co_flags & CO_VARARGS) {
        u = PyTuple_New(argcount - n);
        if (u == NULL) {
            goto fail;
        }
        SETLOCAL(total_args, u);
        for (i = n; i < argcount; i++) {
            x = args[i];
            Py_INCREF(x);
            PyTuple_SET_ITEM(u, i-n, x);
        }
    }

    /* Handle keyword arguments passed as two strided arrays */
    kwcount *= kwstep;
    for (i = 0; i < kwcount; i += kwstep) {
        PyObject **co_varnames;
        PyObject *keyword = kwnames[i];
        PyObject *value = kwargs[i];
        Py_ssize_t j;

        if (keyword == NULL || !PyUnicode_Check(keyword)) {
            PyErr_Format(PyExc_TypeError,
                         "%U() keywords must be strings",
                         co->co_name);
            goto fail;
        }

        /* Speed hack: do raw pointer compares. As names are
           normally interned this should almost always hit. */
        co_varnames = ((PyTupleObject *)(co->co_varnames))->ob_item;
        for (j = 0; j < total_args; j++) {
            PyObject *name = co_varnames[j];
            if (name == keyword) {
                goto kw_found;
            }
        }

        /* Slow fallback, just in case */
        for (j = 0; j < total_args; j++) {
            PyObject *name = co_varnames[j];
            int cmp = PyObject_RichCompareBool( keyword, name, Py_EQ);
            if (cmp > 0) {
                goto kw_found;
            }
            else if (cmp < 0) {
                goto fail;
            }
        }

        assert(j >= total_args);
        if (kwdict == NULL) {
            PyErr_Format(PyExc_TypeError,
                         "%U() got an unexpected keyword argument '%S'",
                         co->co_name, keyword);
            goto fail;
        }

        if (PyDict_SetItem(kwdict, keyword, value) == -1) {
            goto fail;
        }
        continue;

      kw_found:
        if (GETLOCAL(j) != NULL) {
            PyErr_Format(PyExc_TypeError,
                         "%U() got multiple values for argument '%S'",
                         co->co_name, keyword);
            goto fail;
        }
        Py_INCREF(value);
        SETLOCAL(j, value);
    }

    /* Check the number of positional arguments */
    if (argcount > co->co_argcount && !(co->co_flags & CO_VARARGS)) {
        too_many_positional(co, argcount, defcount, fastlocals);
        goto fail;
    }

    /* Add missing positional arguments (copy default values from defs) */
    if (argcount < co->co_argcount) {
        Py_ssize_t m = co->co_argcount - defcount;
        Py_ssize_t missing = 0;
        for (i = argcount; i < m; i++) {
            if (GETLOCAL(i) == NULL) {
                missing++;
            }
        }
        if (missing) {
            missing_arguments(co, missing, defcount, fastlocals);
            goto fail;
        }
        if (n > m)
            i = n - m;
        else
            i = 0;
        for (; i < defcount; i++) {
            if (GETLOCAL(m+i) == NULL) {
                PyObject *def = defs[i];
                Py_INCREF(def);
                SETLOCAL(m+i, def);
            }
        }
    }

    /* Add missing keyword arguments (copy default values from kwdefs) */
    if (co->co_kwonlyargcount > 0) {
        Py_ssize_t missing = 0;
        for (i = co->co_argcount; i < total_args; i++) {
            PyObject *name;
            if (GETLOCAL(i) != NULL)
                continue;
            name = PyTuple_GET_ITEM(co->co_varnames, i);
            if (kwdefs != NULL) {
                PyObject *def = PyDict_GetItem(kwdefs, name);
                if (def) {
                    Py_INCREF(def);
                    SETLOCAL(i, def);
                    continue;
                }
            }
            missing++;
        }
        if (missing) {
            missing_arguments(co, missing, -1, fastlocals);
            goto fail;
        }
    }

    /* Allocate and initialize storage for cell vars, and copy free
       vars into frame. */
    for (i = 0; i < PyTuple_GET_SIZE(co->co_cellvars); ++i) {
        PyObject *c;
        Py_ssize_t arg;
        /* Possibly account for the cell variable being an argument. */
        if (co->co_cell2arg != NULL &&
            (arg = co->co_cell2arg[i]) != CO_CELL_NOT_AN_ARG) {
            c = PyCell_New(GETLOCAL(arg));
            /* Clear the local copy. */
            SETLOCAL(arg, NULL);
        }
        else {
            c = PyCell_New(NULL);
        }
        if (c == NULL)
            goto fail;
        SETLOCAL(co->co_nlocals + i, c);
    }

    /* Copy closure variables to free variables */
    for (i = 0; i < PyTuple_GET_SIZE(co->co_freevars); ++i) {
        PyObject *o = PyTuple_GET_ITEM(closure, i);
        Py_INCREF(o);
        freevars[PyTuple_GET_SIZE(co->co_cellvars) + i] = o;
    }

    /* Handle generator/coroutine/asynchronous generator */
    if (co->co_flags & (CO_GENERATOR | CO_COROUTINE | CO_ASYNC_GENERATOR)) {
        PyObject *gen;
        PyObject *coro_wrapper = tstate->coroutine_wrapper;
        int is_coro = co->co_flags & CO_COROUTINE;

        if (is_coro && tstate->in_coroutine_wrapper) {
            assert(coro_wrapper != NULL);
            PyErr_Format(PyExc_RuntimeError,
                         "coroutine wrapper %.200R attempted "
                         "to recursively wrap %.200R",
                         coro_wrapper,
                         co);
            goto fail;
        }

        /* Don't need to keep the reference to f_back, it will be set
         * when the generator is resumed. */
        Py_CLEAR(f->f_back);

        /* Create a new generator that owns the ready to run frame
         * and return that as the value. */
        if (is_coro) {
            gen = PyCoro_New(f, name, qualname);
        } else if (co->co_flags & CO_ASYNC_GENERATOR) {
            gen = PyAsyncGen_New(f, name, qualname);
        } else {
            gen = PyGen_NewWithQualName(f, name, qualname);
        }
        if (gen == NULL) {
            return NULL;
        }

        _PyObject_GC_TRACK(f);

        if (is_coro && coro_wrapper != NULL) {
            PyObject *wrapped;
            tstate->in_coroutine_wrapper = 1;
            wrapped = PyObject_CallFunction(coro_wrapper, "N", gen);
            tstate->in_coroutine_wrapper = 0;
            return wrapped;
        }

        return gen;
    }
    /* 这里执行指令 */
    retval = PyEval_EvalFrameEx(f,0);

fail: /* Jump here from prelude on failure */

    /* decref'ing the frame can cause __del__ methods to get invoked,
       which can call back into Python.  While we're done with the
       current Python frame (f), the associated C stack is still in use,
       so recursion_depth must be boosted for the duration.
    */
    assert(tstate != NULL);
    if (Py_REFCNT(f) > 1) {
        Py_DECREF(f);
        _PyObject_GC_TRACK(f);
    }
    else {
        ++tstate->recursion_depth;
        Py_DECREF(f);
        --tstate->recursion_depth;
    }
    return retval;
}

static PyObject *
function_call(PyObject *func, PyObject *args, PyObject *kwargs)
{
    PyObject **stack;
    Py_ssize_t nargs;

    stack = &PyTuple_GET_ITEM(args, 0);
    nargs = PyTuple_GET_SIZE(args);
    return _PyFunction_FastCallDict(func, stack, nargs, kwargs);
}

hello = 'nihao'

TARGET(STORE_NAME) {
  PyObject *name = GETITEM(names, oparg);
  PyObject *v = POP();
  PyObject *ns = f->f_locals;
  int err;
  if (ns == NULL) {
    PyErr_Format(PyExc_SystemError,
                 "no locals found when storing %R", name);
    Py_DECREF(v);
    goto error;
  }
  if (PyDict_CheckExact(ns))
    err = PyDict_SetItem(ns, name, v);
  else
    err = PyObject_SetItem(ns, name, v);  /* 将对象存储到当前栈帧中 */
  Py_DECREF(v);
  if (err != 0)
    goto error;
  DISPATCH();
}

err = PyObject_SetItem(ns, name, v);

hello = 'nihao'
print(globals() == locals())

import requests
print(inspect.getsource(requests.get))

def get(url, params=None, **kwargs):
    r"""Sends a GET request.

    :param url: URL for the new :class:`Request` object.
    :param params: (optional) Dictionary or bytes to be sent in the query string for the :class:`Request`.
    :param \*\*kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    kwargs.setdefault('allow_redirects', True)
    return request('get', url, params=params, **kwargs)