diff options
| author | Jarkko Hietaniemi <jhi@iki.fi> | 2003-09-22 09:57:26 +0000 |
|---|---|---|
| committer | Jarkko Hietaniemi <jhi@iki.fi> | 2003-09-22 09:57:26 +0000 |
| commit | 2572cfa649c3092862e45cd336636319a5bff067 (patch) | |
| tree | 6957caefa78ca00f1f41804e342a946941d5d7bf | |
| parent | 0a6556cc61f2da2b12cce544c77d838b8ef992cc (diff) | |
| download | perl-2572cfa649c3092862e45cd336636319a5bff067.tar.gz | |
Integrate:
[ 21311]
Some more perlio doc tweaks based on NI-S.
p4raw-link: @21311 on //depot/perl: cc7ef057bab1579c0576d0a578186a6e5ae298e2
p4raw-id: //depot/maint-5.8/perl@21315
p4raw-integrated: from //depot/perl@21314 'copy in' pod/perliol.pod
(@21295..)
| -rw-r--r-- | pod/perliol.pod | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/pod/perliol.pod b/pod/perliol.pod index eb6433a97a..a2eeed3287 100644 --- a/pod/perliol.pod +++ b/pod/perliol.pod @@ -26,13 +26,13 @@ C, with vtables" approach which may be applied to perl6. =head2 Basic Structure -PerlIO is as a stack of layers. +PerlIO is a stack of layers. The low levels of the stack work with the low-level operating system calls (file descriptors in C) getting bytes in and out, the higher -layers of the stack buffer, filter, and otherwise manipulate the I/O. -Terms I<above> and I<below> are used to refer to the relative -positioning of the stack layers. +layers of the stack buffer, filter, and otherwise manipulate the I/O, +and return characters (or bytes) to Perl. Terms I<above> and I<below> +are used to refer to the relative positioning of the stack layers. A layer contains a "vtable", the table of I/O operations (at C level a table of function pointers), and status flags. The functions in the @@ -44,11 +44,17 @@ bottom the input is requested from the operating system services, then the result is returned up the stack, finally being interpreted as Perl data. +The requests do not necessarily go always all the way down to the +operating system: that's where PerlIO buffering comes into play. + When you do an open() and specify extra PerlIO layers to be deployed, the layers you specify are "pushed" on top of the already existing -default stack. What exact layers are in this default stack depends on -a lot of things: your operating system, Perl version, Perl compile -time configuration, and Perl runtime configuration. See L<PerlIO>, +default stack. One way to see it is that "operating system is +on the left" and "Perl is on the right". + +What exact layers are in this default stack depends on a lot of +things: your operating system, Perl version, Perl compile time +configuration, and Perl runtime configuration. See L<PerlIO>, L<perlrun/PERLIO>, and L<open> for more information. binmode() operates similarly to open(): by default the specified |