原来虚拟机是一颗软件CPU

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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;

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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()

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>>> import sys
>>> frame = sys._getframe()
>>> frame
<frame at 0x10e3706a8, file '<stdin>', 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']

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import sys

pi = 3.14

def square(r):
    frame = sys._getframe()
    while frame:
        print('#', 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(5))

if __name__ == '__main__':
    main()

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# square
Locals: ['r', 'frame']
Globals: ['__name__', '__doc__', '__package__', '__loader__', '__spec__', '__annotations__', '__builtins__', '__file__', '__cached__', 'sys', 'pi', 'square', 'circle_area', 'main']

# circle_area
Locals: ['r']
Globals: ['__name__', '__doc__', '__package__', '__loader__', '__spec__', '__annotations__', '__builtins__', '__file__', '__cached__', 'sys', 'pi', 'square', 'circle_area', 'main']

# main
Locals: []
Globals: ['__name__', '__doc__', '__package__', '__loader__', '__spec__', '__annotations__', '__builtins__', '__file__', '__cached__', 'sys', 'pi', 'square', 'circle_area', 'main']

# <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']

78.5