inject bytecode into python

gistfile1.py

import sys
import dis
import inspect
from byteplay import *

def wearedcode(fcode):
    c = Code.from_code(fcode)
    if c.code[1] == (LOAD_CONST, 'alex'):
        return fcode

    c.code[1:1] = [
                    (LOAD_CONST, u'alex'), (STORE_FAST, 'name'),
                    (LOAD_FAST, 'name'), 
                    (PRINT_ITEM, None), (PRINT_NEWLINE, None),
                  ] 

    return c.to_code()


def trace(frame, event, arg):
    if event != 'call':
        return
    co = frame.f_code
    func_name = co.co_name

    if func_name == "write":
        return

    if func_name == "get":
        import tornado.web
        args = inspect.getargvalues(frame)
        if 'self' in args.locals:
            if isinstance(args.locals['self'], tornado.web.RequestHandler):
                getmethod = args.locals['self'].get
                print(dis.dis(getmethod.__func__.__code__))
                code = getmethod.__func__.__code__
                getmethod.__func__.__code__ = wearedcode(code)
        return

sys.settrace(trace)