# 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, $file); # See comment block above return &$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 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. 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 A typical module using L 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', $VERSION; In other words: replace C by C, remove C from @ISA, change C by C. Do not forget to quote the name of your package on the C line, and add comma (C<,>) before the arguments ($VERSION above). Of course, if @ISA contained only C, there is no need to have the @ISA assignment at all; moreover, if instead of C one uses backward-compatible use vars qw($VERSION @ISA); one can remove this reference to @ISA together with the @ISA assignment If no $VERSION was specified on the C line, the last line becomes XSLoader::load 'YourPackage'; =head2 Backward compatible boilerplate If you want to have your cake and eat it too, you need a more complicated boilerplate. package YourPackage; use vars qw($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 by C, so the compiler does not know that a function XSLoader::load() is present. This boilerplate uses the low-overhead C if present; if used with an antic Perl which has no C, it falls back to using C. =head1 Order of initialization: early load() I section in your XS file (see L). What is described here is equally applicable to L interface.> A sufficiently complicated module using XS would have both Perl code (defined in F) and XS code (defined in F). 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 $VERSION was specified, a sanity check is done to insure that the versions of the F<.pm> and the (compiled) F<.xs> parts are compatible; =item * The XSUBs are made accessible from Perl; =item * If the C section was present in F<.xs> file, the code there is called. =back Consequently, if the code in F<.pm> file makes calls to these XSUBs, it is convenient to have XSUBs installed before the Perl code is defined; for example, this makes prototypes for XSUBs visible to this Perl code. Alternatively, if the C section makes calls to Perl functions (or uses Perl variables) defined in F<.pm> file, they must be defined prior to the call to XSLoader::load() (or bootstrap()). The first situation being much more frequent, it makes sense to rewrite the boilerplate as package YourPackage; use XSLoader; use vars qw($VERSION @ISA); BEGIN { @ISA = qw( OnePackage OtherPackage ); $VERSION = '0.01'; # Put Perl code used in the BOOT: section here XSLoader::load 'YourPackage', $VERSION; } # Put Perl code making calls into XSUBs here =head2 The most hairy case If the interdependence of your C section and Perl code is more complicated than this (e.g., the C section makes calls to Perl functions which make calls to XSUBs with prototypes), get rid of the C section altogether. Replace it with a function onBOOT(), and call it like this: package YourPackage; use XSLoader; use vars qw($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 would put the DLL). If not found, the search for the DLL is transparently delegated to C, 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. =head1 AUTHOR Ilya Zakharevich: extraction from DynaLoader. =cut