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<ppdoc>
<copyright>
Copyright (c) 2001 by Addison Wesley Longman. This
material may be distributed only subject to the terms and
conditions set forth in the Open Publication License, v1.0 or
later (the latest version is presently available at
http://www.opencontent.org/openpub/).
</copyright>
<class name="ObjectSpace" type="module">
<p/>
The <modulename>ObjectSpace</modulename> module contains a number of routines that
interact with the garbage collection facility and allow you to
traverse all living objects with an iterator.
<p/>
<modulename>ObjectSpace</modulename> also provides support for object
finalizers, procs that will be called when a specific object is
about to be destroyed by garbage collection.
<p/>
<codefragment>
<alltt><fullcode><![CDATA[ include ObjectSpace
a = "A"
b = "B"
c = "C"
define_finalizer(a, proc {|id| puts "Finalizer one on #{id}" })
define_finalizer(a, proc {|id| puts "Finalizer two on #{id}" })
define_finalizer(b, proc {|id| puts "Finalizer three on #{id}" })
]]></fullcode>
include<nbsp/>ObjectSpace
<p/>
a<nbsp/>=<nbsp/>"A"
b<nbsp/>=<nbsp/>"B"
c<nbsp/>=<nbsp/>"C"
<p/>
define_finalizer(a,<nbsp/>proc<nbsp/>{|id|<nbsp/>puts<nbsp/>"Finalizer<nbsp/>one<nbsp/>on<nbsp/>#{id}"<nbsp/>})
define_finalizer(a,<nbsp/>proc<nbsp/>{|id|<nbsp/>puts<nbsp/>"Finalizer<nbsp/>two<nbsp/>on<nbsp/>#{id}"<nbsp/>})
define_finalizer(b,<nbsp/>proc<nbsp/>{|id|<nbsp/>puts<nbsp/>"Finalizer<nbsp/>three<nbsp/>on<nbsp/>#{id}"<nbsp/>})
</alltt>
</codefragment>
<em>produces:</em>
<codefragment><alltt>
0x4018d4f0
n<nbsp/>finals=>1
Finalizer<nbsp/>three<nbsp/>on<nbsp/>537684600
0x4018d504
n<nbsp/>finals=>0
Finalizer<nbsp/>one<nbsp/>on<nbsp/>537684610
n<nbsp/>finals=>0
Finalizer<nbsp/>two<nbsp/>on<nbsp/>537684610
</alltt>
</codefragment>
<p/>
<methods type="class">
<p/>
<method name="_id2ref" ref="_id2ref">
<callseq>
ObjectSpace._id2ref( <obj>anId</obj> )
<returns><obj>anObject</obj></returns>
</callseq>
<desc>
<p/>
Converts an object id to a reference to the object.
May not be
called on an object id passed as a parameter to a finalizer.
<p/>
<codefragment>
<fullcode><![CDATA[ s = "I am a string"
r = ObjectSpace._id2ref(s.id)
r == s
]]></fullcode><rubycode>
<tr>
<td><tt>s<nbsp/>=<nbsp/>"I<nbsp/>am<nbsp/>a<nbsp/>string"</tt></td>
<td>»</td>
<td><tt>"I<nbsp/>am<nbsp/>a<nbsp/>string"</tt></td>
</tr>
<tr>
<td><tt>r<nbsp/>=<nbsp/>ObjectSpace._id2ref(s.id)</tt></td>
<td>»</td>
<td><tt>"I<nbsp/>am<nbsp/>a<nbsp/>string"</tt></td>
</tr>
<tr>
<td><tt>r<nbsp/>==<nbsp/>s</tt></td>
<td>»</td>
<td><tt>true</tt></td>
</tr>
</rubycode>
<p/>
</codefragment>
<p/>
</desc>
</method>
<p/>
<method name="define_finalizer" ref="define_finalizer">
<callseq>
ObjectSpace.define_finalizer(
<obj>anObject</obj>, <obj>aProc</obj>=proc()
)
</callseq>
<desc>
<p/>
Adds <obj>aProc</obj> as a finalizer, to be called when <obj>anObject</obj>
is about to be destroyed.
<p/>
</desc>
</method>
<p/>
<method name="each_object" ref="each_object">
<callseq>
ObjectSpace.each_object( <opt>
<obj>aClassOrMod</obj></opt> )
<block>{| anObj | <blockbody>block</blockbody> }</block>
<returns><obj>aFixnum</obj></returns>
</callseq>
<desc>
<p/>
Calls the block once for each living, nonimmediate
object in this Ruby process.
If <obj>aClassOrMod</obj> is specified, calls the block for only those
classes or modules that match (or are a subclass of)
<obj>aClassOrMod</obj>.
Returns the number of objects found.
<p/>
<codefragment>
<alltt><fullcode><![CDATA[ a = 102.7
b = 95
ObjectSpace.each_object(Numeric) {|x| p x }
print "Total count: ", ObjectSpace.each_object {} ,"\n"
]]></fullcode>
a<nbsp/>=<nbsp/>102.7
b<nbsp/>=<nbsp/>95
ObjectSpace.each_object(Numeric)<nbsp/>{|x|<nbsp/>p<nbsp/>x<nbsp/>}
print<nbsp/>"Total<nbsp/>count:<nbsp/>",<nbsp/>ObjectSpace.each_object<nbsp/>{}<nbsp/>,"\n"
</alltt>
</codefragment>
<em>produces:</em>
<codefragment><alltt>
102.7
2.718281828
3.141592654
Total<nbsp/>count:<nbsp/>376
</alltt>
</codefragment>
<p/>
</desc>
</method>
<p/>
<method name="garbage_collect" ref="garbage_collect">
<callseq>
ObjectSpace.garbage_collect
<returns><tt>nil</tt></returns>
</callseq>
<desc>
<p/>
Initiates garbage collection (see module <modulename>GC</modulename> on page 414).
<p/>
</desc>
</method>
<p/>
<method name="undefine_finalizer" ref="undefine_finalizer">
<callseq>
ObjectSpace.undefine_finalizer(
<obj>anObject</obj> )
</callseq>
<desc>
<p/>
Removes all finalizers for <obj>anObject</obj>.
<p/>
</desc>
</method>
<p/>
</methods>
<p/>
</class>
</ppdoc>
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