/usr/share/doc/swi-prolog-doc/UserGuide/sec-C.7.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">

<HTML>
<HEAD>
<TITLE>Programming in XPCE/Prolog: Section C.7</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="sec-C.6.html">
<LINK REL=next HREF="interface.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="sec-C.6.html"><IMG SRC="prev.gif" BORDER=0 ALT="Previous"></A>
<A class="nav" href="interface.html"><IMG SRC="next.gif" BORDER=0 ALT="Next"></A>
</DIV>

<H2><A NAME="sec:C.7"><SPAN class="sec-nr">C.7</SPAN> <SPAN class="sec-title">Summary</SPAN></A></H2>

<P>This section explained the basic object-oriented notions used in
<font size=-1>XPCE</font>. <font size=-1>XPCE</font>'s data is organised 
in <EM>objects</EM> and integers. An object represents a state. An 
object is an instance of a class. A class describes the constituents of 
the state represented in its instances and the methods (actions) 
understood by its instances.

<P>A class is a normal object, as are all the other constituents of <font size=-1>XPCE</font>'s 
programming world: methods, instance variables, messages, expressions, 
etc. This uniform representation allows for inspecting and changing <font size=-1>XPCE</font> 
using the four basic interface predicates from Prolog.

<P>The basic interface predicates pass control from Prolog to <font size=-1>XPCE</font>. 
As control is to be passed from <font size=-1>XPCE</font> to Prolog (for 
example if the user presses a button), a message is send to <A NAME="idx:prolog:651"></A><B>@prolog</B>, 
the only instance of class host. This object will create a goal from the 
message and pass this goal to the Prolog environment.

<P></BODY></HTML>
swi-prolog-doc 5.6.59-1 / usr / share / doc / swi-prolog-doc / UserGuide / sec-C.7.html
