Guido van Rossum schrieb: >On 11/11/05, Ulrich Berning <[EMAIL PROTECTED]> wrote: > > >>For instance, nobody would give the output of a C compiler a different >>extension when different compiler flags are used. >> >> > >But the usage is completely different. With C you explicitly manage >when compilation happens. With Python you don't. When you first run >your program with -O but it crashes, and then you run it again without >-O to enable assertions, you would be very unhappy if the bytecode >cached in a .pyo file would be reused! > > > The other way round makes definitely more sense. At development time, I would never use Python with -O or -OO. I use it only at distribution time, after doing all the tests, to generate optimized bytecode.
However, this problem could be easily solved, if the value of Py_OptimizeFlag would be stored together with the generated bytecode. At import time, the cached bytecode would not be reused if the current value of Py_OptimizeFlag doesn't match the stored value (if the .py file isn't there any longer, we could either raise an exception or we could emit a warning and reuse the bytecode anyway). And if we do this a little bit more clever, we could refuse reusing optimized bytecode if we are running without -O or -OO and ignore assertions and docstrings in unoptimized bytecode when we are running with -O or -OO. >>I would appreciate to see the generation of .pyo files completely >>removed in the next release. >> >> > >You seem to forget the realities of backwards compatibility. While >there are ways to cache bytecode without having multiple extensions, >we probably can't do that until Python 3.0. > > > Please can you explain what backwards compatibility means in this context? Generated bytecode is neither upwards nor backwards compatible. No matter what I try, I always get a 'Bad magic number' when I try to import bytecode generated with a different Python version. The most obvious software, that may depend on the existence of .pyo files are the various freeze/packaging tools like py2exe, py2app, cx_Freeze and Installer. I haven't checked them in detail, but after a short inspection, they seem to be independent of the existence of .pyo files. I can't imagine that there is any other Python software, that depends on the existence of .pyo files, but maybe I'm totally wrong in this wild guess. Ulli _______________________________________________ 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
