Get "code object" of class

[Okko Willeboordse]

To get the "code object" c of my_class I can do;

c = compile(inspect .getsource(my_c lass), "<script>", "exec")

This fails when inspect can't get hold of the source of my_class,
for instance when my_class is in a pyc file.


Is there another way of getting c?

[Matimus]

Re: Get &quot;code object&quot; of class

On Oct 10, 5:50 am, Okko Willeboordse <tr...@willeboo rdse.demon.nl>
wrote:

To get the "code object" c of my_class I can do;
>
c = compile(inspect .getsource(my_c lass), "<script>", "exec")
>
This fails when inspect can't get hold of the source of my_class,
for instance when my_class is in a pyc file.
>
Is there another way of getting c?

Classes don't have a code object that is visible at run-time, at least
not that I know of. The class body is executed when the class is
created and then discarded. _Most_ of the time classes are created at
the module level. However, when a module is compiled, the class does
have a code object which is marshaled and placed inside of the
compiled code. If anybody knows of a simpler way, I would be
interested, but here is _one_ way you can get at the code object if
the class is in a compiled module:

>>f = open("testclass .pyc", "rb")
>>import marshal
>>f.seek(8)
>>o = marshal.load(f)
>>o

<code object <moduleat 00D81DA0, file "testclass. py", line 2>

>>dir(o)

['__class__', '__cmp__', '__delattr__', '__doc__', '__getattribute __',
'__hash__
', '__init__', '__new__', '__reduce__', '__reduce_ex__' , '__repr__',
'__setattr_
_', '__str__', 'co_argcount', 'co_cellvars', 'co_code', 'co_consts',
'co_filenam
e', 'co_firstlineno ', 'co_flags', 'co_freevars', 'co_lnotab',
'co_name', 'co_nam
es', 'co_nlocals', 'co_stacksize', 'co_varnames']

>>o.co_consts

('CBase', <code object CBase at 00D81578, file "testclass. py", line
2>, 'C', <co
de object C at 00D81380, file "testclass. py", line 11>, 'D', <code
object D at 0
0D81530, file "testclass. py", line 15>, None)

>># Get the code object for class 'C'
>>code_obj = o.co_consts[3]

I wouldn't recommend doing it this way though. It is very convoluted
and since the 'dir' method sometimes hides some of the attributes, I
wouldn't be surprised if the code object _was_ available and I just
don't know the name. Why do you even need the classes code object
anyway?

Matt

[Okko Willeboordse]

Re: Get &quot;code object&quot; of class

Thanks,

"Why do you even need the classes code object anyway?"

I need to instantiate and use the class in another process.
This other process doesn't has access to the py or pyc file
holding the m_class (source) code so I can't use pickle.

Something like;
In the first process (that has access to my_class (source) code) I do;

c = compile(inspect .getsource(my_c lass), "<script>", "exec")
s = marshal.dumps(c )
# Send s to other process

In the other process, lacking access, I do;

c = marshal.loads(s )
exec c in my_dict
o = my_dict["my_class"]()
# Use o