old (broken) way inside strings; but it generates this message as a
warning. And in Perl 5.005, this special treatment will cease.
+=head2 Fixed localization of $<digit>, $&, etc.
+
+Perl versions before 5.004 did not always properly localize the
+regex-related special variables. Perl 5.004 does localize them, as
+the documentation has always said it should. This may result in $1,
+$2, etc. no longer being set where existing programs use them.
+
=head2 No resetting of $. on implicit close
The documentation for Perl 5.0 has always stated that C<$.> is I<not>
not be used at all, which allows subroutines to avoid a time-consuming
calculation of a return value if it isn't going to be used.
+=head2 C<eval EXPR> determines value of EXPR in scalar context
+
+Perl (version 5) used to determine the value of EXPR inconsistently,
+sometimes incorrectly using the surrounding context for the determination.
+Now, the value of EXPR (before being parsed by eval) is always determined in
+a scalar context. Once parsed, it is executed as before, by providing
+the context that the scope surrounding the eval provided. This change
+makes the behavior Perl4 compatible, besides fixing bugs resulting from
+the inconsistent behavior. This program:
+
+ @a = qw(time now is time);
+ print eval @a;
+ print '|', scalar eval @a;
+
+used to print something like "timenowis881399109|4", but now (and in perl4)
+prints "4|4".
+
=head2 Changes to tainting checks
A bug in previous versions may have failed to detect some insecure
By default, running out of memory it is not trappable. However, if
compiled for this, Perl may use the contents of C<$^M> as an emergency
pool after die()ing with this message. Suppose that your Perl were
-compiled with -DEMERGENCY_SBRK and used Perl's malloc. Then
+compiled with -DPERL_EMERGENCY_SBRK and used Perl's malloc. Then
$^M = 'a' x (1<<16);
first. Bit eight of each byte is set, except for the last byte, in
which bit eight is clear.
+If 'p' or 'P' are given undef as values, they now generate a NULL
+pointer.
+
Both pack() and unpack() now fail when their templates contain invalid
types. (Invalid types used to be ignored.)
$i
.
+However, it still fails (without a warning) if the foreach is within a
+subroutine:
+
+ my $i;
+ sub foo {
+ foreach $i ( 1 .. 10 ) {
+ write;
+ }
+ }
+ foo;
+ format =
+ my i is @#
+ $i
+ .
+
=back
=head2 New builtin methods
=head2 Malloc enhancements
-Four new compilation flags are recognized by malloc.c. (They have no
-effect if perl is compiled with system malloc().)
-
-=over
-
-=item -DDEBUGGING_MSTATS
-
-If perl is compiled with C<DEBUGGING_MSTATS> defined, you can print
+If perl is compiled with the malloc included with the perl distribution
+(that is, if C<perl -V:d_mymalloc> is 'define') then you can print
memory statistics at runtime by running Perl thusly:
env PERL_DEBUG_MSTATS=2 perl your_script_here
The value of 2 means to print statistics after compilation and on
-exit; with a value of 1, the statistics ares printed only on exit.
+exit; with a value of 1, the statistics are printed only on exit.
(If you want the statistics at an arbitrary time, you'll need to
install the optional module Devel::Peek.)
-=item -DEMERGENCY_SBRK
+Three new compilation flags are recognized by malloc.c. (They have no
+effect if perl is compiled with system malloc().)
+
+=over
+
+=item -DPERL_EMERGENCY_SBRK
If this macro is defined, running out of memory need not be a fatal
error: a memory pool can allocated by assigning to the special
=item "my" variable %s masks earlier declaration in same scope
-(S) A lexical variable has been redeclared in the same scope, effectively
+(W) A lexical variable has been redeclared in the same scope, effectively
eliminating all access to the previous instance. This is almost always
a typographical error. Note that the earlier variable will still exist
until the end of the scope or until all closure referents to it are
=item Applying %s to %s will act on scalar(%s)
-(W) The pattern match (//), substitution (s///), and translation (tr///)
+(W) The pattern match (//), substitution (s///), and transliteration (tr///)
operators work on scalar values. If you apply one of them to an array
or a hash, it will convert the array or hash to a scalar value -- the
length of an array, or the population info of a hash -- and then work on
as an lvalue, which is pretty strange. Perhaps you forgot to
dereference it first. See L<perlfunc/substr>.
+=item Bareword "%s" refers to nonexistent package
+
+(W) You used a qualified bareword of the form C<Foo::>, but
+the compiler saw no other uses of that namespace before that point.
+Perhaps you need to predeclare a package?
+
=item Can't redefine active sort subroutine %s
(F) Perl optimizes the internal handling of sort subroutines and keeps
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