On Wednesday 16 March 2016 05:59, Thomas 'PointedEars' Lahn wrote:
> On a more constructive note, python(1) (CPython) creates a binary (byte-
> code) “.pyc” file from “.py” files when it runs them.
To be precise, it creates a .pyc file when the file is imported, not run.
Just running a Python script doesn't save the byte-code into a file.
> ISTM that you can
> then run the “.pyc” file as if it were the “.py” file
Correct. You can compile the file, delete or move the source code, then run
the .pyc file:
steve@runes:~$ cat test.py
print("Hello World!")
steve@runes:~$ python2.7 -m compileall test.py
Compiling test.py ...
steve@runes:~$ mv test.py test~
steve@runes:~$ python2.7 test.pyc
Hello World!
However byte-code is version-specific: you can only run the .pyc file with
the same version of the interpreter as the one you compiled it with:
steve@runes:~$ python2.6 test.pyc
RuntimeError: Bad magic number in .pyc file
> (if the “.pyc” file
> is given the executable flag, you can even execute it as a standalone
> command, but that might only work on my system).
There may be ways to get it to work, but it doesn't work here:
steve@runes:~$ chmod a+x test.pyc
steve@runes:~$ ./test.pyc
: command not found
./test.pyc: line 2: syntax error near unexpected token `('
./test.pyc: line 2: `$�Vc@s dGHdS(s
Hello
World!N((((stest.py<module>s'
> So apparently you do not have to
> distribute the source code of a program written in Python if you do not
> want to.
Correct. This is a deliberate feature, intentionally supported by the Python
interpreter.
--
Steve
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