perltodo.pod: add perlio todos/thinkabouts

Message-Id: <200612012005.kB1K5Hn3448004@kosh.hut.fi>

p4raw-id: //depot/perl@29435

1 files changed, 15 insertions, 0 deletions

diff --git a/pod/perltodo.pod b/pod/perltodo.pod
index 026f2f6bb7..8626f2a9b5 100644
--- a/pod/perltodo.pod
+++ b/pod/perltodo.pod
@@ -501,6 +501,21 @@ adding the C<SvMAGICAL> check to
 Go through the core and look for similar assumptions that SVs have particular
 types, as all bets are off during global destruction.
 
+=head2 Extend PerlIO and PerlIO::Scalar
+
+PerlIO::Scalar doesn't know how to truncate().  Implementing this
+would require extending the PerlIO vtable.
+
+Similarly the PerlIO vtable doesn't know about formats (write()), or
+about stat(), or chmod()/chown(), utime(), or flock().
+
+(For PerlIO::Scalar it's hard to see what e.g. mode bits or ownership
+would mean.)
+
+PerlIO doesn't do directories or symlinks, either: mkdir(), rmdir(),
+opendir(), closedir(), seekdir(), rewinddir(), glob(); symlink(),
+readlink().
+
 =head1 Tasks that need a knowledge of the interpreter
 
 These tasks would need C knowledge, and knowledge of how the interpreter works,