perlfunc/open: clarify role of mode for undef filename

[perl5.git] / pod / perlfunc.pod

diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod
index e2c9a81..1e32cca 100644 (file)
--- a/pod/perlfunc.pod
+++ b/pod/perlfunc.pod
@@ -1541,10 +1541,9 @@ makes it spring into existence the first time that it is called; see
 L<perlsub>.
 
 Use of L<C<defined>|/defined EXPR> on aggregates (hashes and arrays) is
-deprecated.  It
-used to report whether memory for that aggregate had ever been
-allocated.  This behavior may disappear in future versions of Perl.
-You should instead use a simple test for size:
+no longer supported. It used to report whether memory for that
+aggregate had ever been allocated.  You should instead use a simple
+test for size:
 
     if (@an_array) { print "has array elements\n" }
     if (%a_hash)   { print "has hash members\n"   }
@@ -4350,7 +4349,7 @@ opens the UTF8-encoded file containing Unicode characters;
 see L<perluniintro>.  Note that if layers are specified in the
 three-argument form, then default layers stored in ${^OPEN} (see L<perlvar>;
 usually set by the L<open> pragma or the switch C<-CioD>) are ignored.
-Those layers will also be ignored if you specifying a colon with no name
+Those layers will also be ignored if you specify a colon with no name
 following it.  In that case the default layer for the operating system
 (:raw on Unix, :crlf on Windows) is used.
 
@@ -4406,9 +4405,9 @@ argument being L<C<undef>|/undef EXPR>:
 
     open(my $tmp, "+>", undef) or die ...
 
-opens a filehandle to an anonymous temporary file.  Also using C<< +< >>
-works for symmetry, but you really should consider writing something
-to the temporary file first.  You will need to
+opens a filehandle to a newly created empty anonymous temporary file.
+(This happens under any mode, which makes C<< +> >> the only useful and
+sensible mode to use.)  You will need to
 L<C<seek>|/seek FILEHANDLE,POSITION,WHENCE> to do the reading.
 
 Perl is built using PerlIO by default.  Unless you've
@@ -7406,6 +7405,8 @@ X<split>
 
 Splits the string EXPR into a list of strings and returns the
 list in list context, or the size of the list in scalar context.
+(Prior to Perl 5.11, it also overwrote C<@_> with the list in
+void and scalar context. If you target old perls, beware.)
 
 If only PATTERN is given, EXPR defaults to L<C<$_>|perlvar/$_>.