Python 3.11 bytecode assemble

test.py

from types import FunctionType, CodeType
import dis


def assemble(ops):
    cache = bytes([dis.opmap["CACHE"], 0])
    ret = b""
    for op, arg in ops:
        opc = dis.opmap[op]
        ret += bytes([opc, arg])
        ret += cache * dis._inline_cache_entries[opc]
    return ret


co_code = assemble(
    [
        ("RESUME", 0),
        ("LOAD_FAST", 0),
        ("LOAD_ATTR", 0),
        ("RETURN_VALUE", 0),
    ]
)


def f():
    pass


def getattr(x, y):
    co = f.__code__.replace(
        co_code=co_code,
        co_consts=(None,),
        co_names=(y,),
        co_varnames=("obj",),
        co_nlocals=1,
        co_argcount=1,
        co_flags=3,
        co_stacksize=1,
        co_freevars=(),
    )
    return FunctionType(co, {})(x)


print(getattr(1, "to_bytes"))