64 lines
2.5 KiB
HTML
64 lines
2.5 KiB
HTML
<html>
|
|
|
|
<head>
|
|
<object type="application/x-oleobject" classid="clsid:1e2a7bd0-dab9-11d0-b93a-00c04fc99f9e">
|
|
<param name="Keyword" value="Àáñòðàêòíûé ìåòîä">
|
|
<param name="Keyword" value="abstract">
|
|
</object>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=windows-1251">
|
|
<title></title>
|
|
<link rel="StyleSheet" href="../../default.css">
|
|
</head>
|
|
|
|
<body>
|
|
<H1><span lang="ru">Àáñòðàêòíûå </span><span lang="ru">ì</span>åòîäû è êëàññû</H1>
|
|
<p>Ìåòîäû<span lang="ru">, ïðåäíàçíà÷åííûå äëÿ ïåðåîïðåäåëåíèÿ â ïîäêëàññàõ,
|
|
îáúÿâëÿþòñÿ ñ êëþ÷åâûì ñëîâîì </span><code><b>abstract</b></code>
|
|
<span lang="ru">è íàçûâàþòñÿ àáñòðàêòíûìè. Äàííûå ìåòîäû ÿâëÿþòñÿ
|
|
<a href="virtual.html">âèðòóàëüíûìè</a>,
|
|
íî êëþ÷åâîå ñëîâî </span><code><b>virtual</b></code><span lang="ru">
|
|
èñïîëüçîâàòü íå íóæíî. Íàïðèìåð:</span></p>
|
|
<blockquote>
|
|
<p><code><b>type</b> <br>
|
|
Shape = <b>class</b><br>
|
|
<b>private</b><br>
|
|
x,y: integer;<br>
|
|
<b>public</b><br>
|
|
<b>constructor</b> Create(xx,yy: integer);<br>
|
|
<b>begin</b><br>
|
|
x := xx;<br>
|
|
y := yy;<br>
|
|
<b>end</b>;<br>
|
|
<b>procedure</b> Draw; <b>abstract</b>;<br>
|
|
<b>end</b>;</code></p>
|
|
</blockquote>
|
|
<p><span lang="ru">Êëàññû, ñîäåðæàùèå àáñòðàêòíûå ìåòîäû, òàêæå íàçûâàþòñÿ
|
|
<em>àáñòðàêòíûìè</em>. Ýêçåìïëÿðû ýòèõ êëàññîâ ñîçäàâàòü íåëüçÿ. </span></p>
|
|
<p><span lang="ru">Êëàññû ñ àáñòðàêòíûìè ìåòîäàìè èñïîëüçóþòñÿ êàê
|
|
"ïîëóôàáðèêàòû" äëÿ ñîçäàíèÿ äðóãèõ êëàññîâ. Íàïðèìåð:</span></p>
|
|
<blockquote>
|
|
<p><code><b>type</b> <br>
|
|
Point = <b>class</b>(Shape)<br>
|
|
<b>public</b><br>
|
|
<b>procedure</b> Draw; <b>override</b>;<br>
|
|
<b>begin</b><br>
|
|
PitPixel(x,y,Color.Black);<br>
|
|
<b>end</b>;<br>
|
|
<b>end</b>;</code></p>
|
|
</blockquote>
|
|
<p><span lang="ru">Èñïîëüçîâàíèå </span><code><b>override</b></code>
|
|
<span lang="ru">ïðè ïåðåîïðåäåëåíèè àáñòðàêòíûõ ìåòîäîâ îáÿçàòåëüíî, ïîñêîëüêó
|
|
àáñòðàêòíûå ìåòîäû ÿâëÿþòñÿ ðàçíîâèäíîñòüþ âèðòóàëüíûõ. </span></p>
|
|
<p>Êëàññ ìîæíî ÿâíî îáúÿâèòü àáñòðàêòíûì, èñïîëüçóÿ êëþ÷åâîå ñëîâî <code>
|
|
<strong>abstract</strong></code>. Îáû÷íî àáñòðàêòíûå êëàññû ñîäåðæàò àáñòðàêòíûå
|
|
ìåòîäû, íî íåîáÿçàòåëüíî:</p>
|
|
<blockquote>
|
|
<p><code><b>type</b> <br>
|
|
A = <strong>abstract</strong><b> class</b>(Shape)<br>
|
|
<b>end</b>;</code></p>
|
|
</blockquote>
|
|
<p> </p>
|
|
<p> </p>
|
|
</body>
|
|
|
|
</html> |