Next: 6.2 Standard Modules Up: 6.1 More on Modules Previous: 6.1.1 The Module Search
As an important speed-up of the start-up time for short programs that
use a lot of standard modules, if a file called `spam.pyc' exists
in the directory where `spam.py' is found, this is assumed to
contain an already-``compiled'' version of the module spam. The
modification time of the version of `spam.py' used to create
`spam.pyc' is recorded in `spam.pyc', and the file is
ignored if these don't match.
Normally, you don't need to do anything to create the `spam.pyc' file.
Whenever `spam.py' is successfully compiled, an attempt is made to
write the compiled version to `spam.pyc'. It is not an error if
this attempt fails; if for any reason the file is not written
completely, the resulting `spam.pyc' file will be recognized as
invalid and thus ignored later. The contents of the `spam.pyc'
file is platform independent, so a Python module directory can be
shared by machines of different architectures. (Tip for experts:
the module compileall creates file.pyc files for all modules.)
XXX Should optimization with -O be covered here?