=head1 NAME
-perldelta - what's new for perl v5.6 (as of v5.005_58)
+perldelta - what's new for perl v5.6 (as of v5.005_61)
=head1 DESCRIPTION
This new build option provides a set of macros for all API functions
such that an implicit interpreter/thread context argument is passed to
every API function. As a result of this, something like C<sv_setsv(foo,bar)>
-amounts to a macro invocation that actually translates to
+amounts to a macro invocation that actually translates to something like
C<Perl_sv_setsv(my_perl,foo,bar)>. While this is generally expected
to not have any significant source compatibility issues, the difference
between a macro and a real function call will need to be considered.
+This means that there B<is> a source compatibility issue as a result of
+this if your extensions attempt to use pointers to any of the Perl API
+functions.
+
Note that the above issue is not relevant to the default build of
Perl, whose interfaces continue to match those of prior versions
(but subject to the other options described here).
-For testing purposes, the 5.005_58 release automatically enables
-PERL_IMPLICIT_CONTEXT whenever Perl is built with -Dusethreads or
--Dusemultiplicity.
+PERL_IMPLICIT_CONTEXT is automatically enabled whenever Perl is built
+with one of -Dusethreads, -Dusemultiplicity, or both.
+
+See L<perlguts/"The Perl API"> for detailed information on the
+ramifications of building Perl using this option.
=item C<PERL_POLLUTE_MALLOC>
=head2 Binary Incompatibilities
-The default build of this release can be made binary compatible with the
-5.005 release or its maintenance versions. Add -DPERL_BINCOMPAT_5005
-to ccflags in config.sh to achieve this. See INSTALL for further
-information about adding build flags to config.sh.
+The default build of this release is binary compatible with the 5.005
+release or its maintenance versions.
The usethreads or usemultiplicity builds are B<not> binary compatible
with the corresponding builds in 5.005.
=head2 Lexically scoped warning categories
You can now control the granularity of warnings emitted by perl at a finer
-level using the C<use warning> pragma. See L<warning> and L<perllexwarn>
+level using the C<use warnings> pragma. See L<warnings> and L<perllexwarn>
for details.
=head2 Binary numbers supported
=head2 64-bit support
-Better 64-bit support -- but full support still a distant goal. One
-must Configure with -Duse64bits to get Configure to probe for the
-extent of 64-bit support. Depending on the platform (hints file) more
-or less 64-awareness becomes available. As of 5.005_54 at least
-somewhat 64-bit aware platforms are HP-UX 11 or better, Solaris 2.6 or
-better, IRIX 6.2 or better. Naturally 64-bit platforms like Digital
-Unix and UNICOS also have 64-bit support.
+All platforms that have 64-bit integers either (a) natively as longs
+or ints (b) via special compiler flags (c) using long long are able to
+use "quads" (64-integers) as follows:
+
+=over 4
+
+=item constants in the code
+=item arguments to oct() and hex()
+
+=item arguments to print(), printf() and sprintf()
+
+=item pack() and unpack() "q" format
+
+=item in basic arithmetics
+
+=item vec() (but see the below note about bit arithmetics)
+
+=back
+
+Note that unless you have the case (a) you will have to configure
+and compile Perl using the -Duse64bits Configure flag.
+
+Unfortunately bit arithmetics (&, |, ^, ~, <<, >>) are not 64-bit clean.
+
+Last but not least: note that due to Perl's habit of always using
+floating point numbers the quads are still not true integers.
+When quads overflow their limits (0...18_446_744_073_709_551_615 unsigned,
+-9_223_372_036_854_775_808...9_223_372_036_854_775_807 signed), they
+are silently promoted to floating point numbers, after which they will
+start losing precision (their lower digits).
+
+=head2 Large file support
+
+If you have filesystems that support "large files" (files larger than
+2 gigabytes), you may now also be able to create and access them from Perl.
+
+Note that in addition to requiring a proper file system to do this you
+may also need to adjust your per-process (or even your per-system)
+maximum filesize limits before running Perl scripts that try to handle
+large files, especially if you intend to write such files.
+
+Adjusting your file system/system limits is outside the scope of Perl.
+For process limits, you may try to increase the limits using your
+shell's limit/ulimit command before running Perl. The BSD::Resource
+extension (not included with the standard Perl distribution) may also
+be of use.
+
+(Large file support is also related to 64-bit support, for obvious reasons)
+
=head2 Better syntax checks on parenthesized unary operators
Expressions such as:
were opened only for writing will now produce warnings (just as
writing to read-only filehandles does).
+=head2 Buffered data discarded from input filehandle when dup'ed.
+
+C<open(NEW, "E<lt>&OLD")> now discards any data that was previously
+read and buffered in C<OLD>. The next read operation on C<NEW> will
+return the same data as the corresponding operation on C<OLD>.
+Formerly, it would have returned the data from the start of the
+following disk block instead.
+
=head1 Supported Platforms
=over 4
from the caller's context. C<encoding> is currently the only supported
attribute.
-Lexical warnings pragma, C<use warning;>, to control optional warnings.
+Lexical warnings pragma, C<use warnings;>, to control optional warnings.
C<use filetest> to control the behaviour of filetests (C<-r> C<-w> ...).
Currently only one subpragma implemented, "use filetest 'access';",
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