The PyCodeObject represents the bytecode that is executed by the interpreter. We have seen this in the function PyEval_EvalFrameEx which contains the frame object which internally contains the code to be executed. The structure is defined in the file Include/code.h.

typedef struct {
PyObject_HEAD
int co_argcount; /* #arguments, except *args */
int co_nlocals; /* #local variables */
int co_stacksize; /* #entries needed for evaluation stack */
int co_flags; /* CO_…, see below */
PyObject *co_code; /* instruction opcodes */
PyObject *co_consts; /* list (constants used) */
PyObject *co_names; /* list of strings (names used) */
PyObject *co_varnames; /* tuple of strings (local variable names) */
PyObject *co_freevars; /* tuple of strings (free variable names) */
PyObject *co_cellvars; /* tuple of strings (cell variable names) */
/* The rest doesn’t count for hash/cmp */
PyObject *co_filename; /* string (where it was loaded from) */
PyObject *co_name; /* string (name, for reference) */
int co_firstlineno; /* first source line number */
PyObject *co_lnotab; /* string (encoding addr<->lineno mapping) See
Objects/lnotab_notes.txt for details. */
void *co_zombieframe; /* for optimization only (see frameobject.c) */
PyObject *co_weakreflist; /* to support weakrefs to code objects */
} PyCodeObject;

The most important entry is the co_code entry which contains the python bytecode.

Open the file named codeobject.c and insert a breakpoint in line number 101. Open the debug console and type any expression:

a = 100

We see that a new corresponding CodeObject is created. I would further urge you to debug and understand more about this object.

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