I have a python script.
def hello(self):
return 6
print hello()
Disassembling after compiling in CPython I get
>>> c = compile(open('hello.py').read(), 'hello.py', 'exec')
>>> import dis
>>> dis.dis(c)
1 0 LOAD_CONST 0 (<code object hello at 0x1006c9230, file "hello.py", line 1>)
3 MAKE_FUNCTION 0
6 STORE_NAME 0 (hello)
3 9 LOAD_NAME 0 (hello)
12 CALL_FUNCTION 0
15 PRINT_ITEM
16 PRINT_NEWLINE
17 LOAD_CONST 1 (None)
20 RETURN_VALUE
I'm curious how the <code object hello at 0x1006c9230 ...> is stored inside the CPython code object. There is the co_code function but that only prints out the bytecode instructions. If I serialize the CPython code object I get
>>> import marshal
>>> marshal.dumps(c)
'c\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00@\x00\x00\x00s\x15\x00\x00\x00d\x00\x00\x84\x00\x00Z\x00\x00e\x00\x00\x83\x00\x00GHd\x01\x00S(\x02\x00\x00\x00c\x01\x00\x00\x00\x02\x00\x00\x00\x01\x00\x00\x00C\x00\x00\x00s\n\x00\x00\x00d\x01\x00}\x01\x00|\x01\x00S(\x02\x00\x00\x00Ni\x06\x00\x00\x00(\x00\x00\x00\x00(\x02\x00\x00\x00t\x04\x00\x00\x00selft\x01\x00\x00\x00x(\x00\x00\x00\x00(\x00\x00\x00\x00s\x08\x00\x00\x00hello.pyt\x05\x00\x00\x00hello\x01\x00\x00\x00s\x04\x00\x00\x00\x00\x01\x06\x01N(\x01\x00\x00\x00R\x02\x00\x00\x00(\x00\x00\x00\x00(\x00\x00\x00\x00(\x00\x00\x00\x00s\x08\x00\x00\x00hello.pyt\x08\x00\x00\x00<module>\x01\x00\x00\x00s\x02\x00\x00\x00\t\x03'
I know that
def hello(self):
return 6
is stored somewhere in the dump because if I change it to return 5, one byte in the dump switches from 6 to 5.
1) Is there a way I can access the function body from the CPython code object. The closest I can get it c.names but that only prints out a string. I'm assuming there behind the scenes it is a PyObject that is being serialized as a string. I would also like a confirmation that the function body is indeed stored in c.names.
2) Does marshal dump store the function as bytecode instructions or as a uncompiled literal? I'm leaning toward uncompiled literal as I searched for the opcode \x83 (RETURN_VALUE) and it only appears once in the dump. I believe this implies that there is only one return statement when there should be two: once to exit out of the function hello and once to return None for exiting the script.
Version
Python 2.7.13+ (heads/2.7:96f5020597, May 26 2017, 15:26:13)
[GCC 4.2.1 Compatible Apple LLVM 7.3.0 (clang-703.0.31)] on darwin
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