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   1  package Devel::SelfStubber;
   2  use File::Spec;
   3  require SelfLoader;
   4  @ISA = qw(SelfLoader);
   5  @EXPORT = 'AUTOLOAD';
   6  $JUST_STUBS = 1;
   7  $VERSION = 1.03;
   8  sub Version {$VERSION}
   9  
  10  # Use as
  11  # perl -e 'use Devel::SelfStubber;Devel::SelfStubber->stub(MODULE_NAME,LIB)'
  12  # (LIB defaults to '.') e.g.
  13  # perl -e 'use Devel::SelfStubber;Devel::SelfStubber->stub('Math::BigInt')'
  14  # would print out stubs needed if you added a __DATA__ before the subs.
  15  # Setting $Devel::SelfStubber::JUST_STUBS to 0 will print out the whole
  16  # module with the stubs entered just before the __DATA__
  17  
  18  sub _add_to_cache {
  19      my($self,$fullname,$pack,$lines, $prototype) = @_;
  20      push(@DATA,@{$lines});
  21      if($fullname){push(@STUBS,"sub $fullname $prototype;\n")}; # stubs
  22      '1;';
  23  }
  24  
  25  sub _package_defined {
  26      my($self,$line) = @_;
  27      push(@DATA,$line);
  28  }
  29  
  30  sub stub {
  31      my($self,$module,$lib) = @_;
  32      my($line,$end_data,$fh,$mod_file,$found_selfloader);
  33      $lib ||= File::Spec->curdir();
  34      ($mod_file = $module) =~ s,::,/,g;
  35      $mod_file =~ tr|/|:| if $^O eq 'MacOS';
  36      
  37      $mod_file = File::Spec->catfile($lib, "$mod_file.pm");
  38      $fh = "$module}::DATA";
  39      my (@BEFORE_DATA, @AFTER_DATA, @AFTER_END);
  40      @DATA = @STUBS = ();
  41  
  42      open($fh,$mod_file) || die "Unable to open $mod_file";
  43      local $/ = "\n";
  44      while(defined ($line = <$fh>) and $line !~ m/^__DATA__/) {
  45      push(@BEFORE_DATA,$line);
  46      $line =~ /use\s+SelfLoader/ && $found_selfloader++;
  47      }
  48      (defined ($line) && $line =~ m/^__DATA__/)
  49        || die "$mod_file doesn't contain a __DATA__ token";
  50      $found_selfloader || 
  51      print 'die "\'use SelfLoader;\' statement NOT FOUND!!\n"',"\n";
  52      if ($JUST_STUBS) {
  53          $self->_load_stubs($module);
  54      } else {
  55          $self->_load_stubs($module, \@AFTER_END);
  56      }
  57      if ( fileno($fh) ) {
  58      $end_data = 1;
  59      while(defined($line = <$fh>)) {
  60          push(@AFTER_DATA,$line);
  61      }
  62      }
  63      close($fh);
  64      unless ($JUST_STUBS) {
  65          print @BEFORE_DATA;
  66      }
  67      print @STUBS;
  68      unless ($JUST_STUBS) {
  69          print "1;\n__DATA__\n",@DATA;
  70          if($end_data) { print "__END__ DATA\n",@AFTER_DATA; }
  71          if(@AFTER_END) { print "__END__\n",@AFTER_END; }
  72      }
  73  }
  74  
  75  1;
  76  __END__
  77  
  78  =head1 NAME
  79  
  80  Devel::SelfStubber - generate stubs for a SelfLoading module
  81  
  82  =head1 SYNOPSIS
  83  
  84  To generate just the stubs:
  85  
  86      use Devel::SelfStubber;
  87      Devel::SelfStubber->stub('MODULENAME','MY_LIB_DIR');
  88  
  89  or to generate the whole module with stubs inserted correctly
  90  
  91      use Devel::SelfStubber;
  92      $Devel::SelfStubber::JUST_STUBS=0;
  93      Devel::SelfStubber->stub('MODULENAME','MY_LIB_DIR');
  94  
  95  MODULENAME is the Perl module name, e.g. Devel::SelfStubber,
  96  NOT 'Devel/SelfStubber' or 'Devel/SelfStubber.pm'.
  97  
  98  MY_LIB_DIR defaults to '.' if not present.
  99  
 100  =head1 DESCRIPTION
 101  
 102  Devel::SelfStubber prints the stubs you need to put in the module
 103  before the __DATA__ token (or you can get it to print the entire
 104  module with stubs correctly placed). The stubs ensure that if
 105  a method is called, it will get loaded. They are needed specifically
 106  for inherited autoloaded methods.
 107  
 108  This is best explained using the following example:
 109  
 110  Assume four classes, A,B,C & D.
 111  
 112  A is the root class, B is a subclass of A, C is a subclass of B,
 113  and D is another subclass of A.
 114  
 115                          A
 116                         / \
 117                        B   D
 118                       /
 119                      C
 120  
 121  If D calls an autoloaded method 'foo' which is defined in class A,
 122  then the method is loaded into class A, then executed. If C then
 123  calls method 'foo', and that method was reimplemented in class
 124  B, but set to be autoloaded, then the lookup mechanism never gets to
 125  the AUTOLOAD mechanism in B because it first finds the method
 126  already loaded in A, and so erroneously uses that. If the method
 127  foo had been stubbed in B, then the lookup mechanism would have
 128  found the stub, and correctly loaded and used the sub from B.
 129  
 130  So, for classes and subclasses to have inheritance correctly
 131  work with autoloading, you need to ensure stubs are loaded.
 132  
 133  The SelfLoader can load stubs automatically at module initialization
 134  with the statement 'SelfLoader-E<gt>load_stubs()';, but you may wish to
 135  avoid having the stub loading overhead associated with your
 136  initialization (though note that the SelfLoader::load_stubs method
 137  will be called sooner or later - at latest when the first sub
 138  is being autoloaded). In this case, you can put the sub stubs
 139  before the __DATA__ token. This can be done manually, but this
 140  module allows automatic generation of the stubs.
 141  
 142  By default it just prints the stubs, but you can set the
 143  global $Devel::SelfStubber::JUST_STUBS to 0 and it will
 144  print out the entire module with the stubs positioned correctly.
 145  
 146  At the very least, this is useful to see what the SelfLoader
 147  thinks are stubs - in order to ensure future versions of the
 148  SelfStubber remain in step with the SelfLoader, the
 149  SelfStubber actually uses the SelfLoader to determine which
 150  stubs are needed.
 151  
 152  =cut