1 package lib::core::only;
4 use warnings FATAL => 'all';
8 @INC = @Config{qw(privlibexp archlibexp)};
14 lib::core::only - Remove all non-core paths from @INC to avoid site/vendor dirs
18 use lib::core::only; # now @INC contains only the two core directories
20 To get only the core directories plus the ones for the local::lib in scope:
22 $ perl -mlocal::lib -Mlib::core::only -Mlocal::lib=~/perl5 myscript.pl
24 To attempt to do a self-contained build (but note this will not reliably
25 propagate into subprocesses, see the CAVEATS below):
27 $ PERL5OPT='-mlocal::lib -Mlib::core::only -Mlocal::lib=~/perl5' cpan
29 Please note that it is necessary to use C<local::lib> twice for this to work.
30 First so that C<lib::core::only> doesn't prevent C<local::lib> from loading
31 (it's not currently in core) and then again after C<lib::core::only> so that
32 the local paths are not removed.
36 lib::core::only is simply a shortcut to say "please reduce my @INC to only
37 the core lib and archlib (architecture-specific lib) directories of this perl".
39 You might want to do this to ensure a local::lib contains only the code you
40 need, or to test an L<App::FatPacker|App::FatPacker> tree, or to avoid known
43 You might want to use this to try and install a self-contained tree of perl
44 modules. Be warned that that probably won't work (see L</CAVEATS>).
46 This module was extracted from L<local::lib|local::lib>'s --self-contained
47 feature, and contains the only part that ever worked. I apologise to anybody
48 who thought anything else did.
52 This does B<not> propagate properly across perl invocations like local::lib's
53 stuff does. It can't. It's only a module import, so it B<only affects the
54 specific perl VM instance in which you load and import() it>.
56 If you want to cascade it across invocations, you can set the PERL5OPT
57 environment variable to '-Mlib::core::only' and it'll sort of work. But be
58 aware that taint mode ignores this, so some modules' build and test code
59 probably will as well.
61 You also need to be aware that perl's command line options are not processed
62 in order - -I options take effect before -M options, so
64 perl -Mlib::core::only -Ilib
66 is unlike to do what you want - it's exactly equivalent to:
68 perl -Mlib::core::only
70 If you want to combine a core-only @INC with additional paths, you need to
71 add the additional paths using -M options and the L<lib|lib> module:
73 perl -Mlib::core::only -Mlib=lib
75 # or if you're trying to test compiled code:
77 perl -Mlib::core::only -Mblib
79 For more information on the impossibility of sanely propagating this across
80 module builds without help from the build program, see
81 L<http://www.shadowcat.co.uk/blog/matt-s-trout/tainted-love> - and for ways
82 to achieve the old --self-contained feature's results, look at
83 L<App::FatPacker|App::FatPacker>'s tree function, and at
84 L<App::cpanminus|cpanm>'s --local-lib-contained feature.
88 Matt S. Trout <mst@shadowcat.co.uk>
92 This library is free software under the same terms as perl itself.
96 (c) 2010 the lib::core::only L</AUTHOR> as specified above.