Fixes related to working local $.

To: perl5-porters <perl5-porters@perl.org>
Message-ID: <19990528151118.A289@west-tip.transeda.com>

p4raw-id: //depot/cfgperl@3494

3 files changed, 57 insertions, 61 deletions

diff --git a/ext/IO/lib/IO/Handle.pm b/ext/IO/lib/IO/Handle.pm
index 02595e50a5..30ee2e5989 100644
--- a/ext/IO/lib/IO/Handle.pm
+++ b/ext/IO/lib/IO/Handle.pm
@@ -468,30 +468,12 @@ sub input_record_separator {
 }
 
 sub input_line_number {
-    # local $. does not work properly, so we need to do it some other
-    # way.  We use select, although this is not quite right.  What we
-    # really need to know is the file handle that was the subject of the
-    # last read, seek or tell.
-    my $now  = select;
-    my $keep = $.;
-    my $tell = tell qualify($_[0], caller) if ref($_[0]);
-    my $prev = $.;
-    $. = $_[1] if @_ > 1;
-    no strict "refs";
-    $tell = tell $now;
-    $. = $keep;
-    $prev;
-}
-
-=for when local $. works properly
-sub input_line_number {
     local $.;
     my $tell = tell qualify($_[0], caller) if ref($_[0]);
     my $prev = $.;
     $. = $_[1] if @_ > 1;
     $prev;
 }
-=cut
 
 sub format_page_number {
     my $old = new SelectSaver qualify($_[0], caller) if ref($_[0]);
diff --git a/pod/perlvar.pod b/pod/perlvar.pod
index cb41c96aa0..9402608daf 100644
--- a/pod/perlvar.pod
+++ b/pod/perlvar.pod
@@ -220,8 +220,10 @@ to change that.  An explicit close on a filehandle resets the line
 number.  Because C<E<lt>E<gt>> never does an explicit close, line
 numbers increase across ARGV files (but see examples in L<perlfunc/eof>).
 Consider this variable read-only: setting it does not reposition
-the seek pointer; you'll have to do that on your own.  (Mnemonic:
-many programs use "." to mean the current line number.)  
+the seek pointer; you'll have to do that on your own.  Localizing C<$.>
+has the effect of also localizing Perl's notion of "the last read
+filehandle".  (Mnemonic: many programs use "." to mean the current line
+number.)
 
 =item input_record_separator HANDLE EXPR
 
diff --git a/t/lib/io_linenum.t b/t/lib/io_linenum.t
index 0d28e1898c..e981b951aa 100755
--- a/t/lib/io_linenum.t
+++ b/t/lib/io_linenum.t
@@ -1,19 +1,28 @@
 #!./perl
 
-# test added 29th April 1998 by Paul Johnson (pjcj@transeda.com)
+# test added 29th April 1999 by Paul Johnson (pjcj@transeda.com)
+# updated    28th May   1999 by Paul Johnson
 
-BEGIN {
-    chdir 't' if -d 't';
-    unshift @INC, '../lib' if -d '../lib';
+use strict;
+
+my $File;
+
+BEGIN
+{
+  $File = __FILE__;
+  if (-d 't')
+  {
+    chdir 't';
+    $File =~ s/^t\W+//;                                 # Remove first directory
+  }
+  unshift @INC, '../lib' if -d '../lib';
 }
 
-use strict;
-use IO::File;
 use Test;
 
-BEGIN {
-    plan tests => 9 #, todo => [10]
-}
+BEGIN { plan tests => 12 }
+
+use IO::File;
 
 sub lineno
 {
@@ -21,49 +30,52 @@ sub lineno
   my $l;
   $l .= "$. ";
   $l .= $f->input_line_number;
-  $l .= " $.";
+  $l .= " $.";                     # check $. before and after input_line_number
   $l;
 }
 
-sub OK
-{
-  my $s = select STDOUT;                     # work around a bug in Test.pm 1.04
-  &ok;
-  select $s;
-}
-
 my $t;
 
-open (Q, __FILE__) or die $!;
-my $w = IO::File->new(__FILE__) or die $!;
+open (F, $File) or die $!;
+my $io = IO::File->new($File) or die $!;
+
+<F> for (1 .. 10);
+ok(lineno($io), "10 0 10");
 
-<Q> for (1 .. 10);
-OK(lineno($w), "10 0 10");
+$io->getline for (1 .. 5);
+ok(lineno($io), "5 5 5");
 
-$w->getline for (1 .. 5);
-OK(lineno($w), "5 5 5");
+<F>;
+ok(lineno($io), "11 5 11");
 
-<Q>;
-OK(lineno($w), "11 5 11");
+$io->getline;
+ok(lineno($io), "6 6 6");
 
-$w->getline;
-OK(lineno($w), "6 6 6");
+$t = tell F;                                        # tell F; provokes a warning
+ok(lineno($io), "11 6 11");
 
-$t = tell Q;         # tell Q; provokes a warning - the world is full of bugs...
-OK(lineno($w), "11 6 11");
+<F>;
+ok(lineno($io), "12 6 12");
 
-<Q>;
-OK(lineno($w), "12 6 12");
+select F;
+ok(lineno($io), "12 6 12");
 
-select Q;
-OK(lineno($w), "12 6 12");
+<F> for (1 .. 10);
+ok(lineno($io), "22 6 22");
 
-<Q> for (1 .. 10);
-OK(lineno($w), "22 6 22");
+$io->getline for (1 .. 5);
+ok(lineno($io), "11 11 11");
+
+$t = tell F;
+# We used to have problems here before local $. worked.
+# input_line_number() used to use select and tell.  When we did the
+# same, that mechanism broke.  It should work now.
+ok(lineno($io), "22 11 22");
+
+{
+  local $.;
+  $io->getline for (1 .. 5);
+  ok(lineno($io), "16 16 16");
+}
 
-$w->getline for (1 .. 5);
-OK(lineno($w), "11 11 11");
-__END__
-# This test doesn't work.  It probably won't until local $. does.
-$t = tell Q;
-OK(lineno($w), "22 11 22", 'waiting for local $.');
+ok(lineno($io), "22 16 22");