[Python-Dev] #12982: Should -O be required to *read* .pyo files?

[Alexandre Zani]

On Tue, Jun 12, 2012 at 11:41 AM, Ethan Furman <ethan at stoneleaf.us> wrote:
> Terry Reedy wrote:
>>
>> 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.)
>>
>> So is the import restriction either an accident or obsolete holdover? If
>> so, can removing it be treated as a bugfix and put into current releases, or
>> should it be treated as an enhancement only for a future release?
>>
>> Or is the restriction an intentional reservation of the possibility of
>> making *execution* depend on the flag? Which would mean that the restriction
>> should be kept and only the doc changed?
>
>
> I have no history so cannot say what was supposed to happen, but my $0.02
> would be that if -O is *not* specified then we should try to read .pyc, then
> .pyo, and finally .py.  In other words, I vote for -O being a write flag,
> not a read flag.

What if I change .py?

>
> ~Ethan~
>
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