<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<HTML>
<HEAD>
<TITLE>Programming in XPCE/Prolog</TITLE><LINK REL=home HREF="index.html">
<LINK REL=contents HREF="Contents.html">
<LINK REL=index HREF="DocIndex.html">
<LINK REL=summary HREF="summary.html">
<LINK REL=previous HREF="trouble.html">
<LINK REL=next HREF="summary.html">
<STYLE type="text/css">
/* Style sheet for SWI-Prolog latex2html
*/
dd.defbody
{ margin-bottom: 1em;
}
dt.pubdef
{ background-color: #c5e1ff;
}
pre.code
{ margin-left: 1.5em;
margin-right: 1.5em;
border: 1px dotted;
padding-top: 5px;
padding-left: 5px;
padding-bottom: 5px;
background-color: #f8f8f8;
}
div.navigate
{ text-align: center;
background-color: #f0f0f0;
border: 1px dotted;
padding: 5px;
}
div.title
{ text-align: center;
padding-bottom: 1em;
font-size: 200%;
font-weight: bold;
}
div.author
{ text-align: center;
font-style: italic;
}
div.abstract
{ margin-top: 2em;
background-color: #f0f0f0;
border: 1px dotted;
padding: 5px;
margin-left: 10%; margin-right:10%;
}
div.abstract-title
{ text-align: center;
padding: 5px;
font-size: 120%;
font-weight: bold;
}
div.toc-h1
{ font-size: 200%;
font-weight: bold;
}
div.toc-h2
{ font-size: 120%;
font-weight: bold;
margin-left: 2em;
}
div.toc-h3
{ font-size: 100%;
font-weight: bold;
margin-left: 4em;
}
div.toc-h4
{ font-size: 100%;
margin-left: 6em;
}
span.sec-nr
{
}
span.sec-title
{
}
span.pred-ext
{ font-weight: bold;
}
/* Footnotes */
sup.fn { color: blue; text-decoration: underline; }
span.fn-text: { display: none; }
sup.fn span {display: none;}
sup:hover span
{ display: block !important;
position: absolute; top: auto; left: auto; width: 80%;
color: #000; background: white;
border: 2px solid;
padding: 5px; margin: 10px; z-index: 100;
font-size: smaller;
}
</STYLE>
</HEAD>
<BODY BGCOLOR="white">
<DIV class="navigate"><A class="nav" href="index.html"><IMG SRC="home.gif" BORDER=0 ALT="Home"></A>
<A class="nav" href="Contents.html"><IMG SRC="index.gif" BORDER=0 ALT="Contents"></A>
<A class="nav" href="DocIndex.html"><IMG SRC="yellow_pages.gif" BORDER=0 ALT="Index"></A>
<A class="nav" href="summary.html"><IMG SRC="info.gif" BORDER=0 ALT="Summary"></A>
<A class="nav" href="trouble.html"><IMG SRC="prev.gif" BORDER=0 ALT="Previous"></A>
<A class="nav" href="summary.html"><IMG SRC="next.gif" BORDER=0 ALT="Next"></A>
</DIV>
<H1><A NAME="sec:G"><SPAN class="sec-nr">G</SPAN> <SPAN class="sec-title">Glossary</SPAN></A></H1>
<A NAME="sec:glossary"></A>
<DL>
<DT><A NAME="gloss:attribute"><STRONG>Attribute</STRONG></A></DT>
<DD class="defbody">
A <A class="" href="summary.html#class:attribute">attribute</A> object
is used to define additional properties of an object. The term <A class="" href="glossary.html#gloss:attribute">attribute</A>
is also used as a synonym for <A class="" href="glossary.html#gloss:slot">slot</A>
and <A class="" href="glossary.html#gloss:instance-variable">instance-variable</A>
referring to class defined properties.
</DD>
<DT><A NAME="gloss:clas"><STRONG>Class</STRONG></A></DT>
<DD class="defbody">
A <A class="" href="glossary.html#gloss:clas">class</A> is an object
that acts as a description of other objects called <A class="" href="glossary.html#gloss:instance">instances</A>
of the <A class="" href="glossary.html#gloss:clas">class</A>. Besides
various house-keeping information, a PCE <A class="" href="glossary.html#gloss:clas">class</A>
describes the <A class="" href="glossary.html#gloss:instance-variable">instance-variables</A>
and <A class="" href="glossary.html#gloss:method">methods</A> of its <A class="" href="glossary.html#gloss:instance">instances</A>.
</DD>
<DT><A NAME="gloss:class-variable"><STRONG>Class-Variable</STRONG></A></DT>
<DD class="defbody">
A <A class="" href="glossary.html#gloss:class-variable">class-variable</A>
defines a constant for all instances of the class. Class variables can
be used to define default values for an <A class="" href="glossary.html#gloss:instance-variable">instance-variable</A>.
Initial values for class-variables can be specified in the <CODE>Defaults</CODE>
file. See <A class="sec" href="classvar.html">section 8</A>.
</DD>
<DT><A NAME="gloss:code"><STRONG>Code</STRONG></A></DT>
<DD class="defbody">
A <A class="" href="glossary.html#gloss:code">code</A> object is an
object that represents a procedure. <A class="" href="glossary.html#gloss:code">Code</A>
objects are used for implementation of methods and to associate actions
with various events. For example a button object executes its associated
code object when depressed. The most typical code object is a <A class="" href="summary.html#class:message">message</A>.
</DD>
<DT><A NAME="gloss:control"><STRONG>Control</STRONG></A></DT>
<DD class="defbody">
A <A class="" href="glossary.html#gloss:control">control</A> is a
standard <A class="" href="glossary.html#gloss:gui">GUI</A> object
normally placed in dialog windows. Examples are buttons, text-entry
fields and menus.
</DD>
<DT><A NAME="gloss:event"><STRONG>Event</STRONG></A></DT>
<DD class="defbody">
An <A class="" href="glossary.html#gloss:event">event</A> is an object
that represents an activity of the user: mouse-movements, mouse-buttons,
keyboard activities.
</DD>
<DT><A NAME="gloss:forwarding-of-argument"><STRONG>Forwarding of argument</STRONG></A></DT>
<DD class="defbody">
When code objects are executed it is common to bind the <A class="" href="glossary.html#gloss:var">var</A>
objects <A NAME="idx:arg1:739"></A><B>@arg1</B>, <A NAME="idx:arg2:740"></A><B>@arg2</B>,
... to pass context information for the executing code. For example,
when a method object executes its code it will bind the arguments given
to the method to <A NAME="idx:arg1:741"></A><B>@arg1</B>, ...
</DD>
<DT><A NAME="gloss:function"><STRONG>Function</STRONG></A></DT>
<DD class="defbody">
A <A class="" href="glossary.html#gloss:function">function</A> is a
subclass of class <A class="" href="summary.html#class:code">code</A>
which yields a value when executed. The most important functions are
local variables (<A class="" href="glossary.html#gloss:var">var</A>), <A class="" href="glossary.html#gloss:obtainer">obtainers</A>
and mathetical operations. They may be used as arguments to code
objects. They are executed when the code object is executed or when the
function needs to be converted to a type that does not accept a
function.
</DD>
<DT><A NAME="gloss:get-operation"><STRONG>Get operation</STRONG></A></DT>
<DD class="defbody">
Virtual machine operation to request information from some object.
Started by the Prolog predicate <A NAME="idx:get313:742"></A><A class="pred" href="sec-D.1.html#get/3">get/[3-13]</A>,
when an obtainer is executed or from PCE's built-in functionality.
</DD>
<DT><A NAME="gloss:gui"><STRONG>GUI</STRONG></A></DT>
<DD class="defbody">
Abbreviation for Graphical User Interface.
</DD>
<DT><A NAME="gloss:inheritance"><STRONG>Inheritance</STRONG></A></DT>
<DD class="defbody">
The sharing of definition from a super-class. When a PCE <A class="" href="glossary.html#gloss:clas">class</A>
is created from a <A class="" href="glossary.html#gloss:super-clas">super-class</A>
it is initially a copy of this
<A class="" href="glossary.html#gloss:super-clas">super-class</A>. After
creation, instance variables and methods may be added and/or redefined.
</DD>
<DT><A NAME="gloss:instance"><STRONG>Instance</STRONG></A></DT>
<DD class="defbody">
Synonym for <A class="" href="glossary.html#gloss:object">object</A>,
often use to stress the fact that an object belongs to a particular
class.
</DD>
<DT><A NAME="gloss:instance-variable"><STRONG>Instance-variable</STRONG></A></DT>
<DD class="defbody">
Placeholder for the local-state associated with an <A class="" href="glossary.html#gloss:object">object</A>.
An
<A class="" href="glossary.html#gloss:instance-variable">instance-variable</A>
is associated with a class and has a name and a type. Each of the <A class="" href="glossary.html#gloss:instance">instances</A>
of the class defines a value for the instance variable. Instance
variables are represented by class
<A class="" href="summary.html#class:variable">variable</A>.
</DD>
<DT><A NAME="gloss:message"><STRONG>Message</STRONG></A></DT>
<DD class="defbody">
A <A class="" href="glossary.html#gloss:message">message</A> is an
object representing a <A class="" href="glossary.html#gloss:send-operation">send-operation</A>.
The phrase ``sending a message to X'' is equivalent to ``invoking a get-
or send-operation on X''.
</DD>
<DT><A NAME="gloss:method"><STRONG>Method</STRONG></A></DT>
<DD class="defbody">
A <A class="" href="glossary.html#gloss:method">method</A> maps a <A class="" href="glossary.html#gloss:selector">selector</A>
and a type vector onto an implementation which is either a C-function or
a <A class="" href="glossary.html#gloss:code">code</A> object. PCE
defines both get- and send-methods. If a <A class="" href="glossary.html#gloss:send-operation">send-operation</A>
is invoked on an object, PCE will find a method associated with the
class of the object with a matching <A class="" href="glossary.html#gloss:selector">selector</A>,
check the argument types and invoke the implementation of the method.
</DD>
<DT><A NAME="gloss:object-reference"><STRONG>Object-reference</STRONG></A></DT>
<DD class="defbody">
An <EM>object-reference</EM> is the identifier for a particular
instance. In Prolog <A class="" href="glossary.html#gloss:object-reference">object-references</A>
are represented by
<A NAME="idx:Integer:743"></A><B>@Integer</B> or <A NAME="idx:Atom:744"></A><B>@Atom</B>.
</DD>
<DT><A NAME="gloss:object"><STRONG>Object</STRONG></A></DT>
<DD class="defbody">
An <A class="" href="glossary.html#gloss:object">object</A> is en entity
in PCE's world that is identified by an <A class="" href="glossary.html#gloss:object-reference">object-reference</A>
and has a local state. An object is an
<A class="" href="glossary.html#gloss:instance">instance</A> of a <A class="" href="glossary.html#gloss:clas">class</A>.
The <A class="" href="glossary.html#gloss:clas">class</A> defines both
the constituents of the local state as well as the operations (<A class="" href="glossary.html#gloss:method">methods</A>)
understood by the object.
</DD>
<DT><A NAME="gloss:obtainer"><STRONG>Obtainer</STRONG></A></DT>
<DD class="defbody">
An <A class="" href="glossary.html#gloss:obtainer">obtainer</A> is a <A class="" href="glossary.html#gloss:function">function</A>
which invokes a <A class="" href="glossary.html#gloss:get-operation">get-operation</A>
when evaluated. The class name is `?'.
</DD>
<DT><A NAME="gloss:recogniser"><STRONG>Recogniser</STRONG></A></DT>
<DD class="defbody">
A <A class="" href="glossary.html#gloss:recogniser">recogniser</A>
object parses <A class="" href="glossary.html#gloss:event">events</A>
for a graphical object.
</DD>
<DT><A NAME="gloss:selector"><STRONG>Selector</STRONG></A></DT>
<DD class="defbody">
A <A class="" href="glossary.html#gloss:selector">selector</A> is the
name of a <A class="" href="glossary.html#gloss:send-operation">send-operation</A>
or <A class="" href="glossary.html#gloss:get-operation">get-operation</A>.
</DD>
<DT><A NAME="gloss:send-method"><STRONG>Send Method</STRONG></A></DT>
<DD class="defbody">
Refinement of <A class="" href="summary.html#class:method">method</A>
that maps a <A class="" href="glossary.html#gloss:send-operation">send-operation</A>
onto its implementation. See also <A class="" href="glossary.html#gloss:method">Method</A>
</DD>
<DT><A NAME="gloss:send-operation"><STRONG>Send operation</STRONG></A></DT>
<DD class="defbody">
Virtual machine operation which invokes of a <A class="" href="glossary.html#gloss:send-method">send-method</A>
on some object. Started by the Prolog predicate <A NAME="idx:send212:745"></A><A class="pred" href="sec-7.1.html#send/[2-12]">send/[2-12]</A>,
when an <A class="" href="glossary.html#gloss:message">message</A> is
executed or from PCE's built-in functionality.
</DD>
<DT><A NAME="gloss:slot"><STRONG>Slot</STRONG></A></DT>
<DD class="defbody">
Equivalent to <A class="" href="glossary.html#gloss:instance-variable">instance_variable</A>.
</DD>
<DT><A NAME="gloss:super-clas"><STRONG>Super-class</STRONG></A></DT>
<DD class="defbody">
The <A class="" href="glossary.html#gloss:super-clas">super-class</A> of
a <A class="" href="glossary.html#gloss:clas">class</A> serves as the
initial definition of a <A class="" href="glossary.html#gloss:clas">class</A>.
See also <A class="" href="glossary.html#gloss:inheritance">inheritance</A>.
</DD>
<DT><A NAME="gloss:template-clas"><STRONG>Template-class</STRONG></A></DT>
<DD class="defbody">
User-defined subclass of class <B>template</B>. The refinements
introduced from <B>template</B> can be imported in another user-defined
class using the predicate <A NAME="idx:useclasstemplate1:746"></A><A class="pred" href="sec-7.1.html#use_class_template/1">use_class_template/1</A>.
</DD>
<DT><A NAME="gloss:var"><STRONG>Var</STRONG></A></DT>
<DD class="defbody">
A <A class="" href="glossary.html#gloss:var">var</A> object is a <A class="" href="glossary.html#gloss:function">function</A>.
The commonly used <A class="" href="glossary.html#gloss:var">vars</A>
objects are: <A NAME="idx:arg1:747"></A><B>@arg1</B>, ... (general
argument forwarding), <A NAME="idx:receiver:748"></A><B>@receiver</B>
(receiver or a message), <A NAME="idx:event:749"></A><B>@event</B>
(currently processes event object).
</DD>
</DL>
</BODY></HTML>
