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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 (5.8.1-RC3 as of this writing) builds without changes
under Mac OS X. Under the 10.3 "Panther" release, all self-tests pass,
and all standard features are supported.

Earlier Mac OS X releases did not include a completely thread-safe libc,
so threading is not fully supported. Also, earlier releases included a
somewhat 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 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 will be
significantly greater than either the static library, or Apple's
pre-bound dynamic library.


=head2 Updating Panther

As of this writing, the latest Perl release that has been tested and
approved for inclusion in the 10.3 "Panther" release of Mac OS X is
5.8.1 RC3. It is currently unknown whether the final 5.8.1 release will
be made in time to be tested and included with Panther.

If the final release of Perl 5.8.1 is not made in time to be included
with Panther, it is recommended that you wait for an official Apple
update to the OS, rather than attempting to update it yourself. In most
cases, if you need a newer Perl, it is preferable to install it in some
other location, such as /usr/local or /opt, rather than overwriting the
system Perl.  The default location (no -Dprefix=... specified when running
Configure) is /usr/local.

If you find that you do need to update the system Perl, there is one
potential issue. 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.

Note that this is only an issue when updating from an older build of the
same Perl version. If you're updating from (for example) 5.8.1 to 5.8.2,
this issue won't affect you.


=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").


=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 CDs
(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.


=head1 AUTHOR

This README was written by Sherm Pendley E<lt>sherm@dot-app.orgE<gt>.
The "Starting From Scratch" recipe was contributed by John Montbriand
E<lt>montbriand@apple.comE<gt>.

=head1 DATE

Last modified 2003-09-08.