[Python-Dev] RE: [Patches] [Patch #102915] xreadlines : readlines :: xrange : range

[Tim Peters]

[Guido]
> Quite apart from whether we should enable xreadlines(), could you look
> into doing a similar thing for MSVC stdio?  For most Unix platforms, a
> cop-out answer is "use glibc" -- but for Windows it may pay to do our
> own hack.

There's no question about whether it would pay on Windows, because it pays
big for Perl on Windows.  The question is about cost.  There's no way to
*do* it short of the way Perl does it, which is to write a large pile of
Windows-specific code (roughly the same size and complexity as the glibc
getline implementation -- check it out, it's not trivial, and glibc exploits
compiler inlining to make it bearable) relying on reverse-engineered
accidents of how MS happens to use all the fields from this undocumented
struct (from MS's stdio.h):

struct _iobuf {
        char *_ptr;
        int   _cnt;
        char *_base;
        int   _flag;
        int   _file;
        int   _charbuf;
        int   _bufsiz;
        char *_tmpfname;
        };
typedef struct _iobuf FILE;

in their stdio implementation.  Else it won't play correctly with MS's
stdio.  That's A Project.  Last year I tried extracting the relevant code
from Perl, but, as is usual, gave up after unraveling the third (whatever)
layer of mystery macros with no end in sight.  I bet it would take me a
week.  Is it worth that much to you and DC?  Since the real Windows experts
are hanging out at ActiveState, I bet one of them will volunteer to do it
tonight <wink>.