[Distutils] Re: Add multiple frozen modules

[James C. Ahlstrom]

After writing some code, I see that the library file needs to
be a little different.  We need to add the file size so all fseek()'s
can be done relative to the end.  That enables the file to be appended
to the executable.  The offsets written to the file are from ftell()
and are relative to the beginning.  The length is subtracted on
access.

And I introduced a main dictionary TOC and a different dictionary for
the *.pyc files pyc_dict.  Although that may seem a little fancy, it is
actually easier.  And it is much more extensible.  Data may be
freely written to the main dict TOC without damaging the code for
reading *.pyc using pyc_dict.  And another section (I'm thinking of
Gordon's installer) can be added as yet another dict.  In another 
variation, core Python files are in pyc_dict, but encoded *.pyc
files are in a different dict, and imputils is used to import either.

The Python library file format now is:

   Data... consisting of *.pyc files including their 8-byte header;
   Possibly other data...
   TOC, a marshal'd dictionary table of contents;
   a twelve byte ascii decimal seek offset to the start of TOC, a NULL
byte;
   a twelve byte ascii decimal total file size, a NULL byte;
   a 16-byte magic number to identify the file as a valid Python library
file.

 The TOC (table of contents) is a dictionary containing the following
keys:
   "TIME"      The time the library was created, time.time().
   "ASCTIME"   The ascii time the library was created.
   "VERSION"       The version of the library file format, "1".
   "PYC*VERSION"   The ascii version number of the PYC section,
"19990720".
   "PYC"    A dictionary with keys "name", and values a three-tuple
"tup".
       The "name" is the module name.  This is a plain name such as "os"
       or a dotted name such as "foo.bar".  The "tup[0]" is the seek
offset
       to the data, which is the bytes of the module .pyc file including
       the 8-byte header.  The "tup[1]" is the full path of the .pyc
file.
       The "tup[2]" is an integer used as flag bits.  Flag bit 0x01 is
one
       if the module name refers to a package, in which case the file
       is package.__init__.pyc.

 This format is designed to be extensible.  Just add atoms of data to
TOC.
 To add a another whole section, add another name like "PYC".

I have almost finished makepyl.py, a Python program which creates a
PYL file or lists its contents.  And C-code changes to import.c to
be able to import from a PYL file.  However, I am a little short of
time because I am leaving for two weeks vacation on this Saturday.

Jim Ahlstrom