One more test (does binmode()ing a socket succeed)

[p5sagit/p5-mst-13.2.git] / lib / PerlIO.pm

diff --git a/lib/PerlIO.pm b/lib/PerlIO.pm
index 61a748a..5777679 100644 (file)
--- a/lib/PerlIO.pm
+++ b/lib/PerlIO.pm
@@ -115,11 +115,11 @@ to a such a stream.
 =item raw
 
 The C<:raw> layer is I<defined> as being identical to calling
-C<binmode($fh)> - the stream is made suitable for passing binary
-data i.e. each byte is passed as-is. The stream will still be
-buffered. Unlike earlier versions of perl C<:raw> is I<not> just the
-inverse of C<:crlf> - other layers which would affect the binary nature of
-the stream are also removed or disabled.
+C<binmode($fh)> - the stream is made suitable for passing binary data
+i.e. each byte is passed as-is. The stream will still be
+buffered. Unlike in the earlier versions of Perl C<:raw> is I<not>
+just the inverse of C<:crlf> - other layers which would affect the
+binary nature of the stream are also removed or disabled.
 
 The implementation of C<:raw> is as a pseudo-layer which when "pushed"
 pops itself and then any layers which do not declare themselves as suitable
@@ -204,7 +204,7 @@ translation for text files then the default layers are :
 level layer.)
 
 Otherwise if C<Configure> found out how to do "fast" IO using system's
-stdio, then the default layers are :
+stdio, then the default layers are:
 
   unix stdio
 
@@ -224,6 +224,8 @@ This can be used to see the effect of/bugs in the various layers e.g.
   PERLIO=stdio  ./perl harness
   PERLIO=perlio ./perl harness
 
+For the various value of PERLIO see L<perlrun/PERLIO>.
+
 =head2 Querying the layers of filehandle
 
 The following returns the B<names> of the PerlIO layers on a filehandle.
@@ -231,9 +233,21 @@ The following returns the B<names> of the PerlIO layers on a filehandle.
    my @layers = PerlIO::get_layers($fh); # Or FH, *FH, "FH".
 
 The layers are returned in the order an open() or binmode() call would
-use them.  Note that the stack begins (normally) from C<stdio> or from
-C<perlio>.  Under C<stdio> the platform specific low-level I/O (like
-C<unix>) is not part of the stack, but under C<perlio> it is.
+use them.  Note that the "default stack" depends on the operating
+system and on the perl version.
+
+The following table summarizes the default layers on UNIX-like and
+DOS-like platforms and depending on the setting of the C<$ENV{PERLIO}>:
+
+ PERLIO     UNIX-like                   DOS-like
+ 
+ unset / "" unix perlio / stdio [1]     unix crlf
+ stdio      unix perlio / stdio [1]     stdio
+ perlio     unix perlio                 unix perlio
+ mmap       unix mmap                   unix mmap
+
+ # [1] "stdio" if Configure found out how to do "fast stdio" (depends
+ # on the stdio implementation) and in Perl 5.8, otherwise "unix perlio"
 
 By default the layers from the input side of the filehandle is
 returned, to get the output side use the optional C<output> argument: