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Devel::SelfStubber - generate stubs for a SelfLoading module
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To generate just the stubs:
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<PRE> use Devel::SelfStubber;
Devel::SelfStubber->stub('MODULENAME','MY_LIB_DIR');
</PRE>
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or to generate the whole module with stubs inserted correctly
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<PRE> use Devel::SelfStubber;
$Devel::S
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Devel::SelfStubber prints the stubs you need to put in the module before the
<FONT SIZE=-1>__DATA__</FONT> token (or you can get it to print the entire module with stubs correctly placed). The stubs ensure that if a method is called, it will get loaded. They are needed specifically for inherited autoloaded methods.
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This is best explained using the following example:
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Assume four classes,
<FONT SIZE=-1>A,B,C</FONT> &
<FONT SIZE=-1>D.</FONT>
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<FONT SIZE=-1>A</FONT> is the root class,
<FONT SIZE=-1>B</FONT> is a subclass of
<FONT SIZE=-1>A,</FONT>
<FONT SIZE=-1>C</FONT> is a subclass of
<FONT SIZE=-1>B,</FONT> and
<FONT SIZE=-1>D</FONT> is another subclass of
<FONT SIZE=-1>A.</FONT>
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<PRE> A
/ \
B D
/
C
</PRE>
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If
<FONT SIZE=-1>D</FONT> calls an autoloaded method 'foo' which is defined in class
<FONT SIZE=-1>A,</FONT> then the method is loaded into class
<FONT SIZE=-1>A,</FONT> then executed. If
<FONT SIZE=-1>C</FONT> then calls method 'foo', and that method was reimplemented in class
<FONT SIZE=-1>B,</FONT> but set to be autoloaded, then the lookup mechanism never gets to the
<FONT SIZE=-1>AUTOLOAD</FONT> mechanism in
<FONT SIZE=-1>B</FONT> because it first finds the method already loaded in
<FONT SIZE=-1>A,</FONT> and so erroneously uses that. If the method foo had been stubbed in
<FONT SIZE=-1>B,</FONT> then the lookup mechanism would have found the stub, and correctly loaded and used the sub from
<FONT SIZE=-1>B.</FONT>
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So, for classes and subclasses to have inheritance correctly work with
autoloading, you need to ensure stubs are loaded.
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The SelfLoader can load stubs automatically at module initialization with the statement 'SelfLoader->load_stubs()';, but you may wish to avoid having the stub loading overhead associated with your initialization (though note that the SelfLoader::load_stubs method will be called sooner or later - at latest when the first sub is being autoloaded). In this case, you can put the sub stubs before the
<FONT SIZE=-1>__DATA__</FONT> token. This can be done manually, but this module allows automatic generation of the stubs.
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By default it just prints the stubs, but you can set the global
$Devel::SelfStubber::JUST_STUBS to 0 and it will print out the entire
module with the stubs positioned correctly.
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At the very least, this is useful to see what the SelfLoader thinks are
stubs - in order to ensure future versions of the SelfStubber remain in
step with the SelfLoader, the SelfStubber actually uses the SelfLoader to
determine which stubs are needed.
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