# Generated from XSLoader.pm.PL (resolved %Config::Config value) package XSLoader; $VERSION = "0.02"; # enable debug/trace messages from DynaLoader perl code # $dl_debug = $ENV{PERL_DL_DEBUG} || 0 unless defined $dl_debug; my $dl_dlext = 'so'; package DynaLoader; # 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) && !defined(&dl_error); package XSLoader; sub load { package DynaLoader; die q{XSLoader::load('Your::Module', $Your::Module::VERSION)} unless @_; my($module) = $_[0]; # work with static linking too my $b = "$module\::bootstrap"; goto &$b if defined &$b; 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]; my $c = @modparts; $modlibname =~ s,[\\/][^\\/]+$,, while $c--; # Q&D basename my $file = "$modlibname/auto/$modpname/$modfname.$dl_dlext"; # print STDERR "XSLoader::load for $module ($file)\n" if $dl_debug; my $bs = $file; $bs =~ s/(\.\w+)?(;\d*)?$/\.bs/; # look for .bs 'beside' the library goto retry if not -f $file or -s $bs; my $bootname = "boot_$module"; $bootname =~ s/\W/_/g; @dl_require_symbols = ($bootname); my $boot_symbol_ref; if ($^O eq 'darwin') { 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 # it executed. my $libref = dl_load_file($file, 0) or do { require Carp; Carp::croak("Can't load '$file' for module $module: " . dl_error()); }; push(@dl_librefs,$libref); # record loaded object my @unresolved = dl_undef_symbols(); if (@unresolved) { require Carp; Carp::carp("Undefined symbols present after loading $file: @unresolved\n"); } $boot_symbol_ref = dl_find_symbol($libref, $bootname) or do { require Carp; Carp::croak("Can't find '$bootname' symbol in $file\n"); }; push(@dl_modules, $module); # record loaded module boot: my $xs = dl_install_xsub("${module}::bootstrap", $boot_symbol_ref, $file); # See comment block above push(@DynaLoader::dl_shared_objects, $file); # record files loaded return &$xs(@_); retry: require DynaLoader; goto &DynaLoader::bootstrap_inherit; } 1; __END__ =head1 NAME XSLoader - Dynamically load C libraries into Perl code =head1 SYNOPSIS package YourPackage; use XSLoader; XSLoader::load 'YourPackage', $YourPackage::VERSION; =head1 DESCRIPTION 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 more complicated interface see L<DynaLoader>. Many (most) features of DynaLoader are not implemented in XSLoader, like for example the dl_load_flags is not honored by XSLoader. =head2 Migration from C<DynaLoader> A typical module using L<DynaLoader|DynaLoader> starts like this: package YourPackage; require DynaLoader; our @ISA = qw( OnePackage OtherPackage DynaLoader ); our $VERSION = '0.01'; bootstrap YourPackage $VERSION; Change this to package YourPackage; use XSLoader; our @ISA = qw( OnePackage OtherPackage ); our $VERSION = '0.01'; XSLoader::load 'YourPackage', $VERSION; In other words: replace C<require DynaLoader> by C<use XSLoader>, remove C<DynaLoader> from @ISA, change C<bootstrap> by C<XSLoader::load>. Do not forget to quote the name of your package on the C<XSLoader::load> line, and add comma (C<,>) before the arguments ($VERSION above). Of course, if @ISA contained only C<DynaLoader>, there is no need to have the @ISA assignment at all; moreover, if instead of C<our> one uses backward-compatible use vars qw($VERSION @ISA); one can remove this reference to @ISA together with the @ISA assignment If no $VERSION was specified on the C<bootstrap> line, the last line becomes XSLoader::load 'YourPackage'; =head2 Backward compatible boilerplate If you want to have your cake and eat it too, you need a more complicated boilerplate. package YourPackage; use vars qw($VERSION @ISA); @ISA = qw( OnePackage OtherPackage ); $VERSION = '0.01'; eval { require XSLoader; XSLoader::load('YourPackage', $VERSION); 1; } or do { require DynaLoader; push @ISA, 'DynaLoader'; bootstrap YourPackage $VERSION; }; The parentheses about XSLoader::load() arguments are needed since we replaced C<use XSLoader> by C<require>, so the compiler does not know that a function 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 L<DynaLoader|DynaLoader> interface.> 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 XSLoader::load() (or bootstrap()) has three side effects: =over =item * if $VERSION was specified, a sanity check is done to insure that the versions of the F<.pm> and the (compiled) F<.xs> parts are compatible; =item * The XSUBs are made accessible from Perl; =item * If the C<BOOT:> section was present in F<.xs> file, the code there is called. =back Consequently, if the code in F<.pm> file makes calls to these XSUBs, it is convenient to have XSUBs installed before the Perl code is defined; for example, this makes prototypes for XSUBs visible to this Perl code. Alternatively, if the C<BOOT:> section makes calls to Perl functions (or uses Perl variables) defined in F<.pm> file, they must be defined prior to the call to XSLoader::load() (or bootstrap()). The first situation being much more frequent, it makes sense to rewrite the boilerplate as package YourPackage; use XSLoader; use vars qw($VERSION @ISA); BEGIN { @ISA = qw( OnePackage OtherPackage ); $VERSION = '0.01'; # Put Perl code used in the BOOT: section here XSLoader::load 'YourPackage', $VERSION; } # Put Perl code making calls into XSUBs here =head2 The most hairy case If the interdependence of your C<BOOT:> section and Perl code is more complicated than this (e.g., the C<BOOT:> section makes calls to Perl functions which make calls to XSUBs with prototypes), get rid of the C<BOOT:> section altogether. Replace it with a function onBOOT(), and call it like this: package YourPackage; use XSLoader; use vars qw($VERSION @ISA); BEGIN { @ISA = qw( OnePackage OtherPackage ); $VERSION = '0.01'; XSLoader::load 'YourPackage', $VERSION; } # Put Perl code used in onBOOT() function here; calls to XSUBs are # prototype-checked. onBOOT; # Put Perl initialization code assuming that XS is initialized here =head1 LIMITATIONS 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 @INC list. In particular, this is applicable to the structure of @INC used for testing not-yet-installed extensions. This means that the overhead of running uninstalled extension may be much more than running the same extension after C<make install>. =head1 AUTHOR Ilya Zakharevich: extraction from DynaLoader. =cut