Brett Cannon wrote:
On Tue, Jun 12, 2012 at 2:16 PM, Terry Reedy wrote:
http://bugs.python.org/__issue12982 <http://bugs.python.org/issue12982>
Currently, cpython requires the -O flag to *read* .pyo files as well
as the write them. This is a nuisance to people who receive them
from others, without the source. The originator of the issue quotes
the following from the doc (without giving the location).
"It is possible to have a file called spam.pyc (or spam.pyo when -O
is used) without a file spam.py for the same module. This can be
used to distribute a library of Python code in a form that is
moderately hard to reverse engineer."
There is no warning that .pyo files are viral, in a sense. The user
has to use -O, which is a) a nuisance to remember if he has multiple
scripts and some need it and some not, and b) makes his own .py
files used with .pyo imports cached as .pyo, without docstrings,
like it or not.
Currently, the easiest workaround is to rename .pyo to .pyc and all
seems to work fine, even with a mixture of true .pyc and renamed
.pyo files. (The same is true with the -O flag and no renaming.)
This suggests that there is no current reason for the restriction in
that the *execution* of bytecode is not affected by the -O flag.
(Another workaround might be a custom importer -- but this is not
trivial, apparently.)
In Python 3.3 it's actually trivial.
So is the import restriction either an accident or obsolete holdover?
Neither. .pyo files are actually different from .pyc files in terms of
what bytecode they may emit. Currently -O causes all asserts to be left
out of the bytecode and -OO leaves out all docstrings on top of what -O
does. This makes a difference if you are trying to introspect at the
interpreter prompt or are testing things in development and want those
asserts to be triggered if needed.
But what does this have to do with those cases where *only* the .pyo
file is available, and we are trying to run it? In these cases it would
have to be in the main folder (not __pycache__) which means somebody did
it deliberately.
~Ethan~
_______________________________________________
Python-Dev mailing list
Python-Dev@python.org
http://mail.python.org/mailman/listinfo/python-dev
Unsubscribe:
http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
