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co_pickle , a module to serialize code objects (Python recipe) by Andres Tremols
ActiveState Code (http://code.activestate.com/recipes/212565/)

Compiles a string of python code and returns a printable representation of the byte codes, the resulting string can then be restored back to a code object.

Python, 43 lines
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""" Create portable serialized representations of Python <code> Objects"""

import new
import pickle


def co_dumps(s):
    """pickles a code object,arg s is the string with code
    returns the code object pickled as a string"""
    co = compile(s,'<string>','exec')
    co_tup=[co.co_argcount,co.co_nlocals, co.co_stacksize,co.co_flags,
    co.co_code,co.co_consts,co.co_names,co.co_varnames,co.co_filename,
    co.co_name,co.co_firstlineno,co.co_lnotab]
    return pickle.dumps(co_tup)

def co_dumpf(s,f):
    """similar to co_dumps() but instead of returning the string, writes
    the pickled object to an opened file(f) to be retrieved with co_loadf()"""
    
    co = compile(s,'<string>','exec')
    co_tup=[co.co_argcount,co.co_nlocals, co.co_stacksize,co.co_flags,
    co.co_code,co.co_consts,co.co_names,co.co_varnames,co.co_filename,
    co.co_name,co.co_firstlineno,co.co_lnotab]
    pickle.dump(co_tup,f)
    
def co_loads(s):
    """loads a code object pickled with co_dumps()
    return a code object ready for exec()"""
    r = pickle.loads(s)
    return new.code(r[0],r[1],r[2],r[3],r[4],r[5],r[6],r[7],r[8],r[9],r[10],r[11])

def co_loadf(f):
    """loads a code object from a file"""
    r = pickle.load(f)
    return new.code(r[0],r[1],r[2],r[3],r[4],r[5],r[6],r[7],r[8],r[9],r[10],r[11])


def test():
    string_with_code = 'print "hello co_pickle"'
    pickled_code_object = co_dumps(string_with_code)
    #print code_object
    recovered_code_object = co_loads(pickled_code_object)
    exec(recovered_code_object)

I found several posts in the newsgroups complaining of the inability of the pickle modules to achieve this, the key is to store the code object properties in a tuple. Known Issues: The pickle module is infamous for its speed(or lack of), so its recommended you replace pickle with cpickle, you may also want to add some error checking. Finally,Dealing with code objects is somewhat a esoteric hack so care must be taken.

Tags: shortcuts