# Generated from XSLoader.pm.PL (resolved %Config::Config value)
# enable debug/trace messages from DynaLoader perl code
# $dl_debug = $ENV{PERL_DL_DEBUG} || 0 unless defined $dl_debug;
# No prizes for guessing why we don't say 'bootstrap DynaLoader;' here.
# NOTE: All dl_*.xs (including dl_none.xs) define a dl_error() XSUB
boot_DynaLoader
('DynaLoader') if defined(&boot_DynaLoader
) &&
die q{XSLoader::load('Your::Module', $Your::Module::VERSION)} unless @_;
# work with static linking too
my $b = "$module\::bootstrap";
goto retry unless $module and defined &dl_load_file;
my @modparts = split(/::/,$module);
my $modfname = $modparts[-1];
my $modpname = join('/',@modparts);
my $modlibname = (caller())[1];
$modlibname =~ s,[\\/][^\\/]+$,, while $c--; # Q&D basename
my $file = "$modlibname/auto/$modpname/$modfname.$dl_dlext";
# print STDERR "XSLoader::load for $module ($file)\n" if $dl_debug;
$bs =~ s/(\.\w+)?(;\d*)?$/\.bs/; # look for .bs 'beside' the library
goto retry if not -f $file or -s $bs;
my $bootname = "boot_$module";
@DynaLoader::dl_require_symbols = ($bootname);
if ($boot_symbol_ref = dl_find_symbol(0, $bootname)) {
goto boot; #extension library has already been loaded, e.g. darwin
# Many dynamic extension loading problems will appear to come from
# this section of code: XYZ failed at line 123 of DynaLoader.pm.
# Often these errors are actually occurring in the initialisation
# C code of the extension XS file. Perl reports the error as being
# in this perl code simply because this was the last perl code
my $libref = dl_load_file($file, 0) or do {
Carp::croak("Can't load '$file' for module $module: " . dl_error());
push(@DynaLoader::dl_librefs,$libref); # record loaded object
my @unresolved = dl_undef_symbols();
Carp::carp("Undefined symbols present after loading $file: @unresolved\n");
$boot_symbol_ref = dl_find_symbol($libref, $bootname) or do {
Carp::croak("Can't find '$bootname' symbol in $file\n");
push(@DynaLoader::dl_modules, $module); # record loaded module
my $xs = dl_install_xsub("${module}::bootstrap", $boot_symbol_ref, $file);
# See comment block above
push(@DynaLoader::dl_shared_objects, $file); # record files loaded
my $bootstrap_inherit = DynaLoader->can('bootstrap_inherit') ||
XSLoader->can('bootstrap_inherit');
goto &$bootstrap_inherit;
# Versions of DynaLoader prior to 5.6.0 don't have this function.
local *DynaLoader::isa = *{"$module\::ISA"};
local @DynaLoader::isa = (@DynaLoader::isa, 'DynaLoader');
# Cannot goto due to delocalization. Will report errors on a wrong line?
DynaLoader::bootstrap(@_);
XSLoader - Dynamically load C libraries into Perl code
XSLoader::load 'YourPackage', $YourPackage::VERSION;
This module defines a standard I<simplified> interface to the dynamic
linking mechanisms available on many platforms. Its primary purpose is
to implement cheap automatic dynamic loading of Perl modules.
For a more complicated interface, see L<DynaLoader>. Many (most)
features of C<DynaLoader> are not implemented in C<XSLoader>, like for
example the C<dl_load_flags>, not honored by C<XSLoader>.
=head2 Migration from C<DynaLoader>
A typical module using L<DynaLoader|DynaLoader> starts like this:
our @ISA = qw( OnePackage OtherPackage DynaLoader );
bootstrap YourPackage
$VERSION;
our @ISA = qw( OnePackage OtherPackage );
XSLoader
::load
'YourPackage', $VERSION;
In other words
: replace C
<require DynaLoader
> by C
<use XSLoader
>, remove
C
<DynaLoader
> from C
<@ISA>, change C
<bootstrap
> by C
<XSLoader
::load
>. Do
not
forget to quote the name of your
package on the C
<XSLoader
::load
> line
,
and add comma
(C
<,>) before the arguments
(C
<$VERSION> above
).
Of course
, if C
<@ISA> contained only C
<DynaLoader
>, there is
no need to have
the C
<@ISA> assignment at all
; moreover
, if instead of C
<our> one uses the
use vars
qw($VERSION @ISA);
one can remove this reference to C<@ISA> together with the C<@ISA> assignment.
If no C<$VERSION> was specified on the C<bootstrap> line, the last line becomes
XSLoader::load 'YourPackage';
=head2 Backward compatible boilerplate
If you want to have your cake and eat it too, you need a more complicated
use vars qw($VERSION @ISA);
@ISA = qw( OnePackage OtherPackage );
XSLoader
::load
('YourPackage', $VERSION);
bootstrap YourPackage
$VERSION;
The parentheses about C
<XSLoader
::load
()> arguments are needed since we replaced
C
<use XSLoader
> by C
<require>, so the compiler does
not know that a function
C
<XSLoader
::load
()> is present
.
This boilerplate uses the low
-overhead C
<XSLoader
> if present
; if used with
an antic Perl which has
no C
<XSLoader
>, it falls back to using C
<DynaLoader
>.
=head1 Order of initialization: early load()
I<Skip this section if the XSUB functions are supposed to be called from other
modules only; read it only if you call your XSUBs from the code in your module,
or have a C<BOOT:> section in your XS file (see L<perlxs/"The BOOT: Keyword">).
What is described here is equally applicable to the L<DynaLoader|DynaLoader>
A sufficiently complicated module using XS would have both Perl code (defined
in F<YourPackage.pm>) and XS code (defined in F<YourPackage.xs>). If this
Perl code makes calls into this XS code, and/or this XS code makes calls to
the Perl code, one should be careful with the order of initialization.
The call to C<XSLoader::load()> (or C<bootstrap()>) has three side effects:
if C<$VERSION> was specified, a sanity check is done to ensure that the
versions of the F<.pm> and the (compiled) F<.xs> parts are compatible;
the XSUBs are made accessible from Perl;
if a C<BOOT:> section was present in the F<.xs> file, the code there is called.
Consequently, if the code in the F<.pm> file makes calls to these XSUBs, it is
convenient to have XSUBs installed before the Perl code is defined; for
example, this makes prototypes for XSUBs visible to this Perl code.
Alternatively, if the C<BOOT:> section makes calls to Perl functions (or
uses Perl variables) defined in the F<.pm> file, they must be defined prior to
the call to C<XSLoader::load()> (or C<bootstrap()>).
The first situation being much more frequent, it makes sense to rewrite the
use vars qw($VERSION @ISA);
@ISA = qw( OnePackage OtherPackage );
# Put Perl code used in the BOOT: section here
XSLoader::load 'YourPackage', $VERSION;
# Put Perl code making calls into XSUBs here
=head2 The most hairy case
If the interdependence of your C<BOOT:> section and Perl code is
more complicated than this (e.g., the C<BOOT:> section makes calls to Perl
functions which make calls to XSUBs with prototypes), get rid of the C<BOOT:>
section altogether. Replace it with a function C<onBOOT()>, and call it like
use vars qw($VERSION @ISA);
@ISA = qw( OnePackage OtherPackage );
XSLoader::load 'YourPackage', $VERSION;
# Put Perl code used in onBOOT() function here; calls to XSUBs are
# Put Perl initialization code assuming that XS is initialized here
=item Can't find '%s' symbol in %s
B<(F)> The bootstrap symbol could not be found in the extension module.
=item Can't load '%s' for module %s: %s
B<(F)> The loading or initialisation of the extension module failed.
The detailed error follows.
=item Undefined symbols present after loading %s: %s
B<(W)> As the message says, some symbols stay undefined although the
extension module was correctly loaded and initialised. The list of undefined
=item XSLoader::load('Your::Module', $Your::Module::VERSION)
B<(F)> You tried to invoke C<load()> without any argument. You must supply
a module name, and optionally its version.
To reduce the overhead as much as possible, only one possible location
is checked to find the extension DLL (this location is where C<make install>
would put the DLL). If not found, the search for the DLL is transparently
delegated to C<DynaLoader>, which looks for the DLL along the C<@INC> list.
In particular, this is applicable to the structure of C<@INC> used for testing
not-yet-installed extensions. This means that running uninstalled extensions
may have much more overhead than running the same extensions after
Please report any bugs or feature requests via the perlbug(1) utility.
Ilya Zakharevich originally extracted C<XSLoader> from C<DynaLoader>.
CPAN version is currently maintained by SE<eacute>bastien Aperghis-Tramoni
E<lt>sebastien@aperghis.netE<gt>
Previous maintainer was Michael G Schwern <schwern@pobox.com>
This program is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.