lib/perl5/5.6.1/Devel/SelfStubber.pm

   1 package Devel::SelfStubber;
   2 require SelfLoader;
   3 @ISA = qw(SelfLoader);
   4 @EXPORT = 'AUTOLOAD';
   5 $JUST_STUBS = 1;
   6 $VERSION = '1.02';
   7 sub Version {$VERSION}
   8
   9 # Use as
  10 # perl -e 'use Devel::SelfStubber;Devel::SelfStubber->stub(MODULE_NAME,LIB)'
  11 # (LIB defaults to '.') e.g.
  12 # perl -e 'use Devel::SelfStubber;Devel::SelfStubber->stub('Math::BigInt')'
  13 # would print out stubs needed if you added a __DATA__ before the subs.
  14 # Setting $Devel::SelfStubber::JUST_STUBS to 0 will print out the whole
  15 # module with the stubs entered just before the __DATA__
  16
  17 sub _add_to_cache {
  18     my($self,$fullname,$pack,$lines, $prototype) = @_;
  19     push(@DATA,@{$lines});
  20     if($fullname){push(@STUBS,"sub $fullname $prototype;\n")}; # stubs
  21     '1;';
  22 }
  23
  24 sub _package_defined {
  25     my($self,$line) = @_;
  26     push(@DATA,$line);
  27 }
  28
  29 sub stub {
  30     my($self,$module,$lib) = @_;
  31     my($line,$end,$fh,$mod_file,$found_selfloader);
  32     $lib ||= '.';
  33     ($mod_file = $module) =~ s,::,/,g;
  34
  35     $mod_file = "$lib/$mod_file.pm";
  36     $fh = "${module}::DATA";
  37
  38     open($fh,$mod_file) || die "Unable to open $mod_file";
  39     while(defined ($line = <$fh>) and $line !~ m/^__DATA__/) {
  40         push(@BEFORE_DATA,$line);
  41         $line =~ /use\s+SelfLoader/ && $found_selfloader++;
  42     }
  43     $line =~ m/^__DATA__/ || die "$mod_file doesn't contain a __DATA__ token";
  44     $found_selfloader ||
  45         print 'die "\'use SelfLoader;\' statement NOT FOUND!!\n"',"\n";
  46     $self->_load_stubs($module);
  47     if ( fileno($fh) ) {
  48         $end = 1;
  49         while(defined($line = <$fh>)) {
  50             push(@AFTER_DATA,$line);
  51         }
  52     }
  53     unless ($JUST_STUBS) {
  54         print @BEFORE_DATA;
  55     }
  56     print @STUBS;
  57     unless ($JUST_STUBS) {
  58         print "1;\n__DATA__\n",@DATA;
  59         if($end) { print "__END__\n",@AFTER_DATA; }
  60     }
  61 }
  62
  63 1;
  64 __END__
  65
  66 =head1 NAME
  67
  68 Devel::SelfStubber - generate stubs for a SelfLoading module
  69
  70 =head1 SYNOPSIS
  71
  72 To generate just the stubs:
  73
  74     use Devel::SelfStubber;
  75     Devel::SelfStubber->stub('MODULENAME','MY_LIB_DIR');
  76
  77 or to generate the whole module with stubs inserted correctly
  78
  79     use Devel::SelfStubber;
  80     $Devel::SelfStubber::JUST_STUBS=0;
  81     Devel::SelfStubber->stub('MODULENAME','MY_LIB_DIR');
  82
  83 MODULENAME is the Perl module name, e.g. Devel::SelfStubber,
  84 NOT 'Devel/SelfStubber' or 'Devel/SelfStubber.pm'.
  85
  86 MY_LIB_DIR defaults to '.' if not present.
  87
  88 =head1 DESCRIPTION
  89
  90 Devel::SelfStubber prints the stubs you need to put in the module
  91 before the __DATA__ token (or you can get it to print the entire
  92 module with stubs correctly placed). The stubs ensure that if
  93 a method is called, it will get loaded. They are needed specifically
  94 for inherited autoloaded methods.
  95
  96 This is best explained using the following example:
  97
  98 Assume four classes, A,B,C & D.
  99
 100 A is the root class, B is a subclass of A, C is a subclass of B,
 101 and D is another subclass of A.
 102
 103                         A
 104                        / \
 105                       B   D
 106                      /
 107                     C
 108
 109 If D calls an autoloaded method 'foo' which is defined in class A,
 110 then the method is loaded into class A, then executed. If C then
 111 calls method 'foo', and that method was reimplemented in class
 112 B, but set to be autoloaded, then the lookup mechanism never gets to
 113 the AUTOLOAD mechanism in B because it first finds the method
 114 already loaded in A, and so erroneously uses that. If the method
 115 foo had been stubbed in B, then the lookup mechanism would have
 116 found the stub, and correctly loaded and used the sub from B.
 117
 118 So, for classes and subclasses to have inheritance correctly
 119 work with autoloading, you need to ensure stubs are loaded.
 120
 121 The SelfLoader can load stubs automatically at module initialization
 122 with the statement 'SelfLoader-E<gt>load_stubs()';, but you may wish to
 123 avoid having the stub loading overhead associated with your
 124 initialization (though note that the SelfLoader::load_stubs method
 125 will be called sooner or later - at latest when the first sub
 126 is being autoloaded). In this case, you can put the sub stubs
 127 before the __DATA__ token. This can be done manually, but this
 128 module allows automatic generation of the stubs.
 129
 130 By default it just prints the stubs, but you can set the
 131 global $Devel::SelfStubber::JUST_STUBS to 0 and it will
 132 print out the entire module with the stubs positioned correctly.
 133
 134 At the very least, this is useful to see what the SelfLoader
 135 thinks are stubs - in order to ensure future versions of the
 136 SelfStubber remain in step with the SelfLoader, the
 137 SelfStubber actually uses the SelfLoader to determine which
 138 stubs are needed.
 139
 140 =cut