4
4
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
5
5
<title>Reference Counting</title>
6
<meta name="generator" content="DocBook XSL Stylesheets V1.74.2">
6
<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
7
7
<link rel="home" href="index.html" title="Libbonobo Reference Manual">
8
8
<link rel="up" href="factories.html" title="Objects, Factories, Reference Counting">
9
9
<link rel="prev" href="libbonobo-bonobo-shlib-factory.html" title="bonobo-shlib-factory">
27
27
<th width="100%" align="center">Libbonobo Reference Manual</th>
28
28
<td><a accesskey="n" href="property-bags.html"><img src="right.png" width="24" height="24" border="0" alt="Next"></a></td>
30
<div class="refentry" lang="en">
30
<div class="refentry" title="Reference Counting">
31
31
<a name="refcounting"></a><div class="titlepage"></div>
32
<div class="refsect1" lang="en">
33
<a name="id3007010"></a><h2>Reference Counting</h2>
32
<div class="refsect1" title="Reference Counting">
33
<a name="id2978713"></a><h2>Reference Counting</h2>
35
35
Bonobo component reference counting, version 0.1
36
36
by Michael Meeks <mmeeks@gnu.org>
37
37
and Mike Fleming <mfleming@eazel.com>
39
<div class="refsect2" lang="en">
40
<a name="id3007022"></a><h3>Bonobo Objects</h3>
39
<div class="refsect2" title="Bonobo Objects">
40
<a name="id2978725"></a><h3>Bonobo Objects</h3>
42
42
A bonobo object is a glib object that implements an
43
43
CORBA interface, it also contains a pointer to the
68
68
it can't be fiddled with elsewhere.</p>
71
<div class="refsect2" lang="en">
72
<a name="id3007681"></a><h3>Ref counting</h3>
71
<div class="refsect2" title="Ref counting">
72
<a name="id2979385"></a><h3>Ref counting</h3>
73
73
<p> The only ref count to manipulate is that on the
74
74
aggregate obejct, this is done via the
75
75
<code class="function">bonobo_object_ref / unref</code> pair,
91
91
is a very bad move indeed.</p>
94
<div class="refsect2" lang="en">
95
<a name="id3007733"></a><h3>Reference leaks</h3>
94
<div class="refsect2" title="Reference leaks">
95
<a name="id2979436"></a><h3>Reference leaks</h3>
97
97
Catching reference leaks is evily difficult. The first
98
98
approach is to set environment variable
128
128
worked out where the reference went astray.</p>
131
<div class="refsect2" lang="en">
132
<a name="id3007808"></a><h3>Ref Counting Conventions</h3>
131
<div class="refsect2" title="Ref Counting Conventions">
132
<a name="id2979511"></a><h3>Ref Counting Conventions</h3>
133
133
<p>And now for the important stuff:</p>
134
<div class="refsect3" lang="en">
135
<a name="id3007816"></a><h4>Bonobo Ref Counting</h4>
134
<div class="refsect3" title="Bonobo Ref Counting">
135
<a name="id2979520"></a><h4>Bonobo Ref Counting</h4>
136
136
<p>The Bonobo ref count convention is as follows.
137
137
(Mild rewording; same meaning as before)</p>
138
<div class="orderedlist"><ol type="1">
139
<li><p> A function returning an object,
138
<div class="orderedlist"><ol class="orderedlist" type="1">
139
<li class="listitem"><p> A function returning an object,
140
140
either as the return value or by-reference,
141
141
must always add a reference before returning.
142
142
(Alternately: the callee must create a
143
143
reference to the returned object that the
144
144
caller owns)</p></li>
145
<li><p> A function that accepts a bonobo
145
<li class="listitem"><p> A function that accepts a bonobo
146
146
object as an in/out parameter must unreference
147
147
the originally passed object once if the
148
148
function wishes to change the value of the
149
149
in/out parameter. (The function must ref()
150
150
new objects returned via this in/out in
151
151
accordance with [1]) </p></li>
152
<li><p> An object passed into a function
152
<li class="listitem"><p> An object passed into a function
153
153
needs only be ref()'d if the ifunction wishes
154
154
to retain a reference to the object beyond the
155
155
scope of the function call.</p></li>
161
161
casual code observers, and thus may cause hidden
162
162
side-effects.</p>
164
<div class="refsect3" lang="en">
165
<a name="id3007868"></a><h4>CORBA Ref-counting</h4>
164
<div class="refsect3" title="CORBA Ref-counting">
165
<a name="id2979572"></a><h4>CORBA Ref-counting</h4>
166
166
<p>Since the ORB also maintains reference counts
167
167
per interface handle, should you be returning a
168
168
reference to an object it is imperative to</p>
181
181
So to return an Unknown from a impl you can simply:</p>
182
182
<pre class="programlisting">
183
183
return bonobo_object_dup_ref (corba_object, ev);</pre>
184
<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
184
<div class="warning" title="Warning" style="margin-left: 0.5in; margin-right: 0.5in;">
185
185
<h3 class="title">Warning</h3>
186
186
<p>there is a caveat with this approach which is this:</p>
187
187
<p>If you construct a BonoboObject in an impl_
205
205
inserting it into a BonoboObjectClient.</p>
208
<div class="refsect3" lang="en">
209
<a name="id3007953"></a><h4>Ref counting and one-way methods</h4>
208
<div class="refsect3" title="Ref counting and one-way methods">
209
<a name="id2979656"></a><h4>Ref counting and one-way methods</h4>
210
210
<p>While the ORB has built in support for correct
211
211
referencing on 1 way methods, the Bonobo reference
212
212
count does not; hence if you wish to hand a bonobo
added
removed
doc/api/html/refcounting.html
