Python虛擬機棧幀對象及獲取源碼學習

typedef struct _frame {
    PyObject_VAR_HEAD
    struct _frame *f_back;      /* previous frame, or NULL */
    PyCodeObject *f_code;       /* code segment */
    PyObject *f_builtins;       /* builtin symbol table (PyDictObject) */
    PyObject *f_globals;        /* global symbol table (PyDictObject) */
    PyObject *f_locals;         /* local symbol table (any mapping) */
    PyObject **f_valuestack;    /* points after the last local */
    /* Next free slot in f_valuestack.  Frame creation sets to f_valuestack.
       Frame evaluation usually NULLs it, but a frame that yields sets it
       to the current stack top. */
    PyObject **f_stacktop;
    PyObject *f_trace;          /* Trace function */
    char f_trace_lines;         /* Emit per-line trace events? */
    char f_trace_opcodes;       /* Emit per-opcode trace events? */
    /* Borrowed reference to a generator, or NULL */
    PyObject *f_gen;
    int f_lasti;                /* Last instruction if called */
    /* Call PyFrame_GetLineNumber() instead of reading this field
       directly.  As of 2.3 f_lineno is only valid when tracing is
       active (i.e. when f_trace is set).  At other times we use
       PyCode_Addr2Line to calculate the line from the current
       bytecode index. */
    int f_lineno;               /* Current line number */
    int f_iblock;               /* index in f_blockstack */
    char f_executing;           /* whether the frame is still executing */
    PyTryBlock f_blockstack[CO_MAXBLOCKS]; /* for try and loop blocks */
    PyObject *f_localsplus[1];  /* locals+stack, dynamically sized */
} PyFrameObject;

pi = 3.14
def square(r):
    return r ** 2
def circle_area(r):
    return pi * square(r)
def main():
    print(circle_area(5))
if __name__ == '__main__':
    main()

>>> import sys
>>> frame = sys._getframe()
>>> frame
<frame at 0x00000183FA78F870, file '<pyshell#1>', line 1, code <module>>
>>> dir(frame)
['__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'clear', 'f_back', 'f_builtins', 'f_code', 'f_globals', 'f_lasti', 'f_lineno', 'f_locals', 'f_trace', 'f_trace_lines', 'f_trace_opcodes']

>>> import sys
>>> pi = 3.14
>>> def square(r):
        frame = sys._getframe()
        while frame:
            print('name:', frame.f_code.co_name)
            print('Locals', list(frame.f_locals.keys()))
            print('Globals', list(frame.f_globals.keys()))
            print('===========')
            frame = frame.f_back
        return r ** 2
>>> def circle_area(r):
        return pi * square(r)
>>> def main():
        print(circle_area(2))
>>> if __name__ == '__main__':
        main()
name: square
Locals ['r', 'frame']
Globals ['__name__', '__doc__', '__package__', '__loader__', '__spec__', '__annotations__', '__builtins__', '__file__', '__cached__', 'sys', 'pi', 'square', 'circle_area', 'main']
===========
name: circle_area
Locals ['r']
Globals ['__name__', '__doc__', '__package__', '__loader__', '__spec__', '__annotations__', '__builtins__', '__file__', '__cached__', 'sys', 'pi', 'square', 'circle_area', 'main']
===========
name: main
Locals []
Globals ['__name__', '__doc__', '__package__', '__loader__', '__spec__', '__annotations__', '__builtins__', '__file__', '__cached__', 'sys', 'pi', 'square', 'circle_area', 'main']
===========
name: <module>
Locals ['__name__', '__doc__', '__package__', '__loader__', '__spec__', '__annotations__', '__builtins__', '__file__', '__cached__', 'sys', 'pi', 'square', 'circle_area', 'main']
Globals ['__name__', '__doc__', '__package__', '__loader__', '__spec__', '__annotations__', '__builtins__', '__file__', '__cached__', 'sys', 'pi', 'square', 'circle_area', 'main']
===========
12.56

>>> try:
        1 / 0
    except Exception as e:
        print(e.__traceback__.tb_frame)
<frame at 0x000002440D95BC50, file '<pyshell#5>', line 4, code <module>>

>>> def getframe():
        try:
            1 / 0
        except Exception as e:
            return e.__traceback__.tb_frame.f_back

PyObject *
PyEval_EvalCodeEx(PyObject *_co, PyObject *globals, PyObject *locals,
                  PyObject *const *args, int argcount,
                  PyObject *const *kws, int kwcount,
                  PyObject *const *defs, int defcount,
                  PyObject *kwdefs, PyObject *closure);

PyObject *
PyEval_EvalCode(PyObject *co, PyObject *globals, PyObject *locals);

PyObject *
PyEval_EvalFrame(PyFrameObject *f);
PyObject *
PyEval_EvalFrameEx(PyFrameObject *f, int throwflag);
PyObject* _Py_HOT_FUNCTION
_PyEval_EvalFrameDefault(PyFrameObject *f, int throwflag);