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1 | package Devel::SelfStubber; |
2 | require SelfLoader; |
3 | @ISA = qw(SelfLoader); |
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4 | @EXPORT = 'AUTOLOAD'; |
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5 | $JUST_STUBS = 1; |
6 | $VERSION = 1.01; sub Version {$VERSION} |
7 | |
8 | # Use as |
9 | # perl -e 'use Devel::SelfStubber;Devel::SelfStubber->stub(MODULE_NAME,LIB)' |
10 | # (LIB defaults to '.') e.g. |
11 | # perl -e 'use Devel::SelfStubber;Devel::SelfStubber->stub('Math::BigInt')' |
12 | # would print out stubs needed if you added a __DATA__ before the subs. |
13 | # Setting $Devel::SelfStubber::JUST_STUBS to 0 will print out the whole |
14 | # module with the stubs entered just before the __DATA__ |
15 | |
16 | sub _add_to_cache { |
17 | my($self,$fullname,$pack,$lines, $prototype) = @_; |
18 | push(@DATA,@{$lines}); |
19 | if($fullname){push(@STUBS,"sub $fullname $prototype;\n")}; # stubs |
20 | '1;'; |
21 | } |
22 | |
23 | sub _package_defined { |
24 | my($self,$line) = @_; |
25 | push(@DATA,$line); |
26 | } |
27 | |
28 | sub stub { |
29 | my($self,$module,$lib) = @_; |
30 | my($line,$end,$fh,$mod_file,$found_selfloader); |
31 | $lib ||= '.'; |
32 | ($mod_file = $module) =~ s,::,/,g; |
33 | |
34 | $mod_file = "$lib/$mod_file.pm"; |
35 | $fh = "${module}::DATA"; |
36 | |
37 | open($fh,$mod_file) || die "Unable to open $mod_file"; |
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38 | while(defined ($line = <$fh>) and $line !~ m/^__DATA__/) { |
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39 | push(@BEFORE_DATA,$line); |
40 | $line =~ /use\s+SelfLoader/ && $found_selfloader++; |
41 | } |
42 | $line =~ m/^__DATA__/ || die "$mod_file doesn't contain a __DATA__ token"; |
43 | $found_selfloader || |
44 | print 'die "\'use SelfLoader;\' statement NOT FOUND!!\n"',"\n"; |
45 | $self->_load_stubs($module); |
46 | if ( fileno($fh) ) { |
47 | $end = 1; |
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48 | while(defined($line = <$fh>)) { |
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49 | push(@AFTER_DATA,$line); |
50 | } |
51 | } |
52 | unless ($JUST_STUBS) { |
53 | print @BEFORE_DATA; |
54 | } |
55 | print @STUBS; |
56 | unless ($JUST_STUBS) { |
57 | print "1;\n__DATA__\n",@DATA; |
58 | if($end) { print "__END__\n",@AFTER_DATA; } |
59 | } |
60 | } |
61 | |
62 | 1; |
63 | __END__ |
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64 | |
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65 | =head1 NAME |
66 | |
67 | Devel::SelfStubber - generate stubs for a SelfLoading module |
68 | |
69 | =head1 SYNOPSIS |
70 | |
71 | To generate just the stubs: |
72 | |
73 | use Devel::SelfStubber; |
74 | Devel::SelfStubber->stub('MODULENAME','MY_LIB_DIR'); |
75 | |
76 | or to generate the whole module with stubs inserted correctly |
77 | |
78 | use Devel::SelfStubber; |
79 | $Devel::SelfStubber::JUST_STUBS=0; |
80 | Devel::SelfStubber->stub('MODULENAME','MY_LIB_DIR'); |
81 | |
82 | MODULENAME is the Perl module name, e.g. Devel::SelfStubber, |
83 | NOT 'Devel/SelfStubber' or 'Devel/SelfStubber.pm'. |
84 | |
85 | MY_LIB_DIR defaults to '.' if not present. |
86 | |
87 | =head1 DESCRIPTION |
88 | |
89 | Devel::SelfStubber prints the stubs you need to put in the module |
90 | before the __DATA__ token (or you can get it to print the entire |
91 | module with stubs correctly placed). The stubs ensure that if |
92 | a method is called, it will get loaded. They are needed specifically |
93 | for inherited autoloaded methods. |
94 | |
95 | This is best explained using the following example: |
96 | |
97 | Assume four classes, A,B,C & D. |
98 | |
99 | A is the root class, B is a subclass of A, C is a subclass of B, |
100 | and D is another subclass of A. |
101 | |
102 | A |
103 | / \ |
104 | B D |
105 | / |
106 | C |
107 | |
108 | If D calls an autoloaded method 'foo' which is defined in class A, |
109 | then the method is loaded into class A, then executed. If C then |
110 | calls method 'foo', and that method was reimplemented in class |
111 | B, but set to be autoloaded, then the lookup mechanism never gets to |
112 | the AUTOLOAD mechanism in B because it first finds the method |
113 | already loaded in A, and so erroneously uses that. If the method |
114 | foo had been stubbed in B, then the lookup mechanism would have |
115 | found the stub, and correctly loaded and used the sub from B. |
116 | |
117 | So, for classes and subclasses to have inheritance correctly |
118 | work with autoloading, you need to ensure stubs are loaded. |
119 | |
120 | The SelfLoader can load stubs automatically at module initialization |
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121 | with the statement 'SelfLoader-E<gt>load_stubs()';, but you may wish to |
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122 | avoid having the stub loading overhead associated with your |
123 | initialization (though note that the SelfLoader::load_stubs method |
124 | will be called sooner or later - at latest when the first sub |
125 | is being autoloaded). In this case, you can put the sub stubs |
126 | before the __DATA__ token. This can be done manually, but this |
127 | module allows automatic generation of the stubs. |
128 | |
129 | By default it just prints the stubs, but you can set the |
130 | global $Devel::SelfStubber::JUST_STUBS to 0 and it will |
131 | print out the entire module with the stubs positioned correctly. |
132 | |
133 | At the very least, this is useful to see what the SelfLoader |
134 | thinks are stubs - in order to ensure future versions of the |
135 | SelfStubber remain in step with the SelfLoader, the |
136 | SelfStubber actually uses the SelfLoader to determine which |
137 | stubs are needed. |
138 | |
139 | =cut |