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=head1 NAME

README.macosx - Perl under Mac OS X

=head1 SYNOPSIS

This document briefly describes perl under Mac OS X.


=head1 DESCRIPTION

The latest Perl release (5.8.8 as of this writing) builds without changes
under Mac OS X. Under 10.3 "Panther" and newer OS versions, all self-tests
pass, and all standard features are supported.

Earlier Mac OS X releases (10.2 "Jaguar" and older) did not include a
completely thread-safe libc, so threading is not fully supported. Also,
earlier releases included a buggy libdb, so some of the DB_File tests
are known to fail on those releases.


=head2 Installation Prefix

The default installation location for this release uses the traditional
UNIX directory layout under /usr/local. This is the recommended location
for most users, and will leave the Apple-supplied Perl and its modules
undisturbed.

Using an installation prefix of '/usr' will result in a directory layout
that mirrors that of Apple's default Perl, with core modules stored in
'/System/Library/Perl/${version}', CPAN modules stored in
'/Library/Perl/${version}', and the addition of
'/Network/Library/Perl/${version}' to @INC for modules that are stored
on a file server and used by many Macs.


=head2 SDK support

First, export the path to the SDK into the build environment:

    export SDK=/Developer/SDKs/MacOSX10.3.9.sdk

Use an SDK by exporting some additions to Perl's 'ccflags' and '..flags'
config variables:

    ./Configure -Accflags="-nostdinc -B$SDK/usr/include/gcc \
                           -B$SDK/usr/lib/gcc -isystem$SDK/usr/include \
                           -F$SDK/System/Library/Frameworks" \
                -Aldflags="-Wl,-syslibroot,$SDK" \
                -de

=head2 Universal Binary support

To compile perl as a universal binary (built for both ppc and intel), export
the SDK variable as above, selecting the 10.4u SDK:

    export SDK=/Developer/SDKs/MacOSX10.4u.sdk

In addition to the compiler flags used to select the SDK, also add the flags
for creating a universal binary:

    ./Configure -Accflags="-arch i686 -arch ppc -nostdinc -B$SDK/usr/include/gcc \
                           -B$SDK/usr/lib/gcc -isystem$SDK/usr/include \
                           -F$SDK/System/Library/Frameworks" \
                -Aldflags="-arch i686 -arch ppc -Wl,-syslibroot,$SDK" \
                -de

In Leopard (MacOSX 10.5.6 at the time of this writing) you must use the 10.5 SDK:

    export SDK=/Developer/SDKs/MacOSX10.5.sdk

You can use the same compiler flags you would use with the 10.4u SDK.

Keep in mind that these compiler and linker settings will also be used when
building CPAN modules. For XS modules to be compiled as a universal binary, any
libraries it links to must also be universal binaries. The system libraries that
Apple includes with the 10.4u SDK are all universal, but user-installed libraries
may need to be re-installed as universal binaries.

=head2 64-bit PPC support

Follow the instructions in F<INSTALL> to build perl with support for 64-bit 
integers (C<use64bitint>) or both 64-bit integers and 64-bit addressing
(C<use64bitall>). In the latter case, the resulting binary will run only
on G5-based hosts.

Support for 64-bit addressing is experimental: some aspects of Perl may be
omitted or buggy. Note the messages output by F<Configure> for further 
information. Please use C<perlbug> to submit a problem report in the
event that you encounter difficulties.

When building 64-bit modules, it is your responsiblity to ensure that linked
external libraries and frameworks provide 64-bit support: if they do not,
module building may appear to succeed, but attempts to use the module will
result in run-time dynamic linking errors, and subsequent test failures.
You can use C<file> to discover the architectures supported by a library:

    $ file libgdbm.3.0.0.dylib 
    libgdbm.3.0.0.dylib: Mach-O fat file with 2 architectures
    libgdbm.3.0.0.dylib (for architecture ppc):      Mach-O dynamically linked shared library ppc
    libgdbm.3.0.0.dylib (for architecture ppc64):    Mach-O 64-bit dynamically linked shared library ppc64

Note that this issue precludes the building of many Macintosh-specific CPAN
modules (C<Mac::*>), as the required Apple frameworks do not provide PPC64
support. Similarly, downloads from Fink or Darwinports are unlikely to provide
64-bit support; the libraries must be rebuilt from source with the appropriate
compiler and linker flags. For further information, see Apple's
I<64-Bit Transition Guide> at 
L<http://developer.apple.com/documentation/Darwin/Conceptual/64bitPorting/index.html>.

=head2 libperl and Prebinding

Mac OS X ships with a dynamically-loaded libperl, but the default for
this release is to compile a static libperl. The reason for this is
pre-binding. Dynamic libraries can be pre-bound to a specific address in
memory in order to decrease load time. To do this, one needs to be aware
of the location and size of all previously-loaded libraries. Apple
collects this information as part of their overall OS build process, and
thus has easy access to it when building Perl, but ordinary users would
need to go to a great deal of effort to obtain the information needed
for pre-binding.

You can override the default and build a shared libperl if you wish
(S<Configure ... -Duseshrlib>), but the load time on pre-10.4 OS
releases will be greater than either the static library, or Apple's
pre-bound dynamic library.

With 10.4 "Tiger" and newer, Apple has all but eliminated the performance
penalty for non-prebound libraries.


=head2 Updating Apple's Perl

In a word - don't, at least without a *very* good reason. Your scripts
can just as easily begin with "#!/usr/local/bin/perl" as with
"#!/usr/bin/perl". Scripts supplied by Apple and other third parties as
part of installation packages and such have generally only been tested
with the /usr/bin/perl that's installed by Apple.

If you find that you do need to update the system Perl, one issue worth
keeping in mind is the question of static vs. dynamic libraries. If you
upgrade using the default static libperl, you will find that the dynamic
libperl supplied by Apple will not be deleted. If both libraries are
present when an application that links against libperl is built, ld will
link against the dynamic library by default. So, if you need to replace
Apple's dynamic libperl with a static libperl, you need to be sure to
delete the older dynamic library after you've installed the update.


=head2 Known problems

If you have installed extra libraries such as GDBM through Fink
(in other words, you have libraries under F</sw/lib>), or libdlcompat
to F</usr/local/lib>, you may need to be extra careful when running
Configure to not to confuse Configure and Perl about which libraries
to use.  Being confused will show up for example as "dyld" errors about
symbol problems, for example during "make test". The safest bet is to run
Configure as

    Configure ... -Uloclibpth -Dlibpth=/usr/lib

to make Configure look only into the system libraries.  If you have some
extra library directories that you really want to use (such as newer
Berkeley DB libraries in pre-Panther systems), add those to the libpth:

    Configure ... -Uloclibpth -Dlibpth='/usr/lib /opt/lib'

The default of building Perl statically may cause problems with complex
applications like Tk: in that case consider building shared Perl

    Configure ... -Duseshrplib

but remember that there's a startup cost to pay in that case (see above
"libperl and Prebinding").

Starting with Tiger (Mac OS X 10.4), Apple shipped broken locale files for
the eu_ES locale (Basque-Spain).  In previous releases of Perl, this resulted in
failures in the C<lib/locale> test. These failures have been supressed
in the current release of Perl by making the test ignore the broken locale.
If you need to use the eu_ES locale, you should contact Apple support.

=head2 MacPerl

Quite a bit has been written about MacPerl, the Perl distribution for
"Classic MacOS" - that is, versions 9 and earlier of MacOS. Because it
runs in environment that's very different from that of UNIX, many things
are done differently in MacPerl. Modules are installed using a different
procedure, Perl itself is built differently, path names are different,
etc.

From the perspective of a Perl programmer, Mac OS X is more like a
traditional UNIX than Classic MacOS. If you find documentation that
refers to a special procedure that's needed for MacOS that's drastically
different from the instructions provided for UNIX, the MacOS
instructions are quite often intended for MacPerl on Classic MacOS. In
that case, the correct procedure on Mac OS X is usually to follow the
UNIX instructions, rather than the MacPerl instructions.


=head2 Carbon

MacPerl ships with a number of modules that are used to access the
classic MacOS toolbox. Many of these modules have been updated to use
Mac OS X's newer "Carbon" toolbox, and are available from CPAN in the
"Mac::Carbon" module.


=head2 Cocoa

There are two ways to use Cocoa from Perl. Apple's PerlObjCBridge
module, included with Mac OS X, can be used by standalone scripts to
access Foundation (i.e. non-GUI) classes and objects.

An alternative is CamelBones, a framework that allows access to both
Foundation and AppKit classes and objects, so that full GUI applications
can be built in Perl. CamelBones can be found on SourceForge, at
L<http://www.sourceforge.net/projects/camelbones/>.


=head1 Starting From Scratch

Unfortunately it is not that difficult somehow manage to break one's
Mac OS X Perl rather severely.  If all else fails and you want to
really, B<REALLY>, start from scratch and remove even your Apple Perl
installation (which has become corrupted somehow), the following
instructions should do it.  B<Please think twice before following
these instructions: they are much like conducting brain surgery to
yourself.  Without anesthesia.>  We will B<not> come to fix your system
if you do this.

First, get rid of the libperl.dylib:

    # cd /System/Library/Perl/darwin/CORE
    # rm libperl.dylib

Then delete every .bundle file found anywhere in the folders:

    /System/Library/Perl
    /Library/Perl

You can find them for example by

    # find /System/Library/Perl /Library/Perl -name '*.bundle' -print

After this you can either copy Perl from your operating system media
(you will need at least the /System/Library/Perl and /usr/bin/perl),
or rebuild Perl from the source code with C<Configure -Dprefix=/usr
-Dusershrplib> NOTE: the C<-Dprefix=/usr> to replace the system Perl
works much better with Perl 5.8.1 and later, in Perl 5.8.0 the
settings were not quite right.

"Pacifist" from CharlesSoft (L<http://www.charlessoft.com/>) is a nice
way to extract the Perl binaries from the OS media, without having to
reinstall the entire OS.


=head1 AUTHOR

This README was written by Sherm Pendley E<lt>sherm@dot-app.orgE<gt>,
and subsequently updated by Dominic Dunlop E<lt>domo@computer.orgE<gt>.
The "Starting From Scratch" recipe was contributed by John Montbriand
E<lt>montbriand@apple.comE<gt>.

=head1 DATE

Last modified 2006-02-24.