How to force creation of a .pyc?

[Nick Smallbone]

mrstephengross wrote:
> I would like to distribute a python program, but only in .pyc form (so
> that people cannot simply look at my code). Is there a way to do this?
> I've read up a little on the logic by which python creates .pyc's, and
> it sounds like python requires the main executed program to be in .py
> format. Any ideas?
>

If your main program is in main.py, you could perhaps launch it with
python -c "import main", or make another file which just does import
main. Then you could keep just the .pycs/.pyos.

But it's possible for a determined user to recover a lot of information
about the source code. For example, if I write

def foo(a):
   for i in range(a):
      print i

then

>>> dis.dis(foo)
  2           0 SETUP_LOOP              25 (to 28)
              3 LOAD_GLOBAL              0 (range)
              6 LOAD_FAST                0 (a)
              9 CALL_FUNCTION            1
             12 GET_ITER
        >>   13 FOR_ITER                11 (to 27)
             16 STORE_FAST               1 (i)

  3          19 LOAD_FAST                1 (i)
             22 PRINT_ITEM
             23 PRINT_NEWLINE
             24 JUMP_ABSOLUTE           13
        >>   27 POP_BLOCK
        >>   28 LOAD_CONST               0 (None)
             31 RETURN_VALUE

where 0..12 makes an iterator for range(a), 16..19 updates i and 22..23
prints it out. It would be possible to turn it into equivalent source
code. Decompyle (from
http://ftp.debian.org/debian/pool/main/d/decompyle/decompyle_2.3.2.orig.tar.gz)
can even do that.