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21<h1>Glossary</h1>
22
23<dl>
24
25<dt class="glossary"><strong>ancestor</strong><a name="ancestor"></a></dt>
26<dd>A class or parent that contributes (via inheritance) to the definition of an object. The ancestors of an object are its class and all the superclasses of its class (in class-based hierarchies) or its parent and the ancestors of its parent (in prototype-based hierarchies).</dd>
27
28<dt class="glossary"><strong>category</strong><a name="category"></a></dt>
29<dd>A set of predicates directives and clauses that can be imported by any object.</dd>
30
31<dt class="glossary"><strong>class</strong><a name="class"></a></dt>
32<dd>An object that defines the common predicates of a set of objects (its instances).</dd>
33
34<dd><dl>
35
36<dt class="glossary"><strong>abstract class</strong><a name="abstractclass"></a></dt>
37<dd>A class that cannot be instantiated. Usually used to store common predicates that are inherited by other classes.</dd>
38
39<dt class="glossary"><strong>metaclass</strong><a name="metaclass"></a></dt>
40<dd>The class of a class, when we see it as an object. Metaclass instances are themselves classes. In a reflexive system any metaclass is also an object.</dd>
41
42<dt class="glossary"><strong>subclass</strong><a name="subclass"></a></dt>
43<dd>A class that is a specialization, direct or indirectly, of another class.</dd>
44
45<dt class="glossary"><strong>superclass</strong><a name="superclass"></a></dt>
46<dd>A class from each another class is a specialization (directly or indirectly via another class).</dd>
47
48</dl></dd>
49
50<dt class="glossary"><strong>directive</strong><a name="directive"></a></dt>
51<dd>A Prolog term that affects the interpretation of Prolog code. Directives are represented using the <code>:-/1</code> prefix functor.</dd>
52
53<dd><dl>
54
55<dt class="glossary"><strong>entity directive</strong><a name="entity_directive"></a></dt>
56<dd>A directive that affects how Logtalk entities (objects, protocols, or categories) are used or compiled.</dd>
57
58<dt class="glossary"><strong>predicate directive</strong><a name="predicate_directive"></a></dt>
59<dd>A directive that affects how predicates are called or compiled.</dd>
60
61</dl></dd>
62
63<dt class="glossary"><strong>encapsulation</strong><a name="encapsulation"></a></dt>
64<dd>The hiding of an object implementation. This promotes software reuse by isolating users from implementation details.</dd>
65
66<dt class="glossary"><strong>entity</strong><a name="entity"></a></dt>
67<dd>Generic name for Logtalk compilation units: objects, categories, and protocols.</dd>
68
69<dt class="glossary"><strong>event</strong><a name="event"></a></dt>
70<dd>The sending of a message to an object. An event can be expressed as an ordered tuple: <code>(Event, Object, Message, Sender)</code>. Logtalk distinguish between the sending of a message - <code>before</code> event - and the return of control to the sender - <code>after</code> event.</dd>
71
72<dt class="glossary"><strong>identity</strong><a name="identity"></a></dt>
73<dd>Property of an entity that distinguish it from every other entity. In Logtalk an entity identity can be an atom or a compound term. All Logtalk entities, objects, protocols and categories share the same name space.</dd>
74
75<dt class="glossary"><strong>inheritance</strong><a name="inheritance"></a></dt>
76<dd>An object inherits predicate directives and clauses from other objects that it extends or specializes. If an object extends other object then we have a prototype-based inheritance. If an object specializes or instantiates another object we have a class-based inheritance.</dd>
77
78<dd><dl>
79
80<dt class="glossary"><strong>private inheritance</strong><a name="private_inheritance"></a></dt>
81<dd>All public and protected predicates are inherited as private predicates.</dd>
82
83<dt class="glossary"><strong>protected inheritance</strong><a name="protected_inheritance"></a></dt>
84<dd>All public predicates are inherited as protected. No change for protected or private predicates.</dd>
85
86<dt class="glossary"><strong>public inheritance</strong><a name="public_inheritance"></a></dt>
87<dd>All inherited predicates maintain the declared scope.</dd>
88
89</dl></dd>
90
91<dt class="glossary"><strong>instance</strong><a name="instance"></a></dt>
92<dd>The same as object. This term is used when we want to emphasize that an object characteristics are defined by another object (its class).</dd>
93
94<dt class="glossary"><strong>instantiation</strong><a name="instantiation"></a></dt>
95<dd>The process of creating a new class instance.</dd>
96
97<dt class="glossary"><strong>message</strong><a name="message"></a></dt>
98<dd>A request for a service, sent to an object. In more logical terms, a message can be seen as a request for proof construction using an object's predicates.</dd>
99
100<dt class="glossary"><strong>metainterpreter</strong><a name="metainterpreter"></a></dt>
101<dd>A program capable of running other programs written in the same language.</dd>
102
103<dt class="glossary"><strong>method</strong><a name="method"></a></dt>
104<dd>Set of predicate clauses used to answer a message sent to an object. Logtalk uses dynamic binding to find which method to run to answer a message.</dd>
105
106<dt class="glossary"><strong>monitor</strong><a name="monitor"></a></dt>
107<dd>Any object that is notified when a spied event occurs. The spied events can be set by the monitor or by any other object.</dd>
108
109<dt class="glossary"><strong>object</strong><a name="object"></a></dt>
110<dd>An entity characterized by an identity and a set of predicate directives and clauses. In Logtalk objects can be either static or dynamic, like any other Prolog code.</dd>
111
112<dd><dl>
113
114<dt class="glossary"><strong>parametric object</strong><a name="parametric"></a></dt>
115<dd>An object whose name is a compound term containing free variables that can be used to parameterize the object predicates.</dd>
116
117</dl></dd>
118
119
120<dt class="glossary"><strong>parent</strong><a name="parent"></a></dt>
121<dd>An object that is extended by another object.</dd>
122
123<dt class="glossary"><strong>predicate</strong><a name="predicate"></a></dt>
124<dd>Predicates describe what is true about the application domain. A predicate is identified by its name and number of arguments using the notation <code>&lt;name&gt;/&lt;nargs&gt;</code>.</dd>
125
126<dd><dl>
127
128<dt class="glossary"><strong>local predicate</strong><a name="local_predicate"></a></dt>
129<dd>A predicate that is defined in an object (or in a category) but that is not listed in a scope directive. These predicates behave like private predicates but are invisible to the reflection methods.</dd>
130
131<dt class="glossary"><strong>metapredicate</strong><a name="metapredicate"></a></dt>
132<dd>A predicate where one of its arguments will be called as a goal. For instance, <code>findall/3</code> and <code>call/1</code> are Prolog built-ins metapredicates.</dd>
133
134<dt class="glossary"><strong>private predicate</strong><a name="private_predicate"></a></dt>
135<dd>A predicate that can only be called from the object that contains the scope directive.</dd>
136
137<dt class="glossary"><strong>protected predicate</strong><a name="protected_predicate"></a></dt>
138<dd>A predicate that can only be called from the object containing the scope directive or from an object that inherits the predicate.</dd>
139
140<dt class="glossary"><strong>public predicate</strong><a name="public_predicate"></a></dt>
141<dd>A predicate that can be called from any object.</dd>
142
143<dt class="glossary"><strong>visible predicate</strong><a name="visible_predicate"></a></dt>
144<dd>A predicate that is declared for an object, a built-in method, or a Prolog or Logtalk built-in predicate.</dd>
145
146</dl></dd>
147
148<dt class="glossary"><strong>profiler</strong><a name="profiler"></a></dt>
149<dd>A program that collects data about other program performance.</dd>
150
151<dt class="glossary"><strong>protocol</strong><a name="protocol"></a></dt>
152<dd>A set of predicates directives that can be implemented by an object or a category (or extended by another protocol).</dd>
153
154<dt class="glossary"><strong>prototype</strong><a name="protocol"></a></dt>
155<dd>A self-describing object that may extend or be extended by other objects.</dd>
156
157<dt class="glossary"><strong>self</strong><a name="self"></a></dt>
158<dd>The original object that received the message under execution.</dd>
159
160<dt class="glossary"><strong>sender</strong><a name="sender"></a></dt>
161<dd>An object that sends a message to other object.</dd>
162
163<dt class="glossary"><strong>specialization</strong><a name="specialization"></a></dt>
164<dd>A class is specialized by constructing a new class that inherit its predicates and possibly add new ones.</dd>
165
166<dt class="glossary"><strong>this</strong><a name="this"></a></dt>
167<dd>The object that contains the predicate clause under execution.</dd>
168
169</dl>
170
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176Copyright &copy; <a href="mailto:pmoura@logtalk.org">Paulo Moura</a> &mdash; <a href="http://www.logtalk.org">Logtalk.org</a>
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