Help/Core/RefCopy.html

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
   2 <html>
   3 <head>
   4 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
   5 <meta http-equiv="Content-Style-Type" content="text/css">
   6 <title></title>
   7 <meta name="Generator" content="Cocoa HTML Writer">
   8 <meta name="CocoaVersion" content="949.35">
   9 <style type="text/css">
  10 p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica}
  11 p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; min-height: 14.0px}
  12 p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 9.0px Monaco; color: #bf0000}
  13 p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 9.0px Monaco; color: #000000; min-height: 12.0px}
  14 p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 9.0px Monaco; color: #000000}
  15 span.s1 {font: 18.0px Helvetica}
  16 span.s2 {color: #0000ff}
  17 span.s3 {color: #0000bf}
  18 span.s4 {color: #bf0000}
  19 span.s5 {color: #000000}
  20 span.Apple-tab-span {white-space:pre}
  21 </style>
  22 </head>
  23 <body>
  24 <p class="p1"><span class="s1"><b>RefCopy<span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span></b></span><b><span class="Apple-tab-span">      </span>a reference to the copy of a value</b></p>
  25 <p class="p2"><b></b><br></p>
  26 <p class="p1"><b>superclass: Ref</b></p>
  27 <p class="p2"><br></p>
  28 <p class="p1">A Ref<span class="Apple-converted-space">  </span>instance is an object with a single slot named 'value' that serves as a holder of<span class="Apple-converted-space">  </span>an object.</p>
  29 <p class="p1">RefCopy, in difference to Ref, returns only copies of the value when <b>next</b> is called.<span class="Apple-converted-space"> </span></p>
  30 <p class="p1">This can be useful when the original is to be kept unchanged.</p>
  31 <p class="p2"><br></p>
  32 <p class="p1">see <a href="Ref.html"><span class="s2">Ref</span></a> for other methods.</p>
  33 <p class="p2"><br></p>
  34 <p class="p3">// example:<span class="Apple-converted-space">   </span></p>
  35 <p class="p4"><br></p>
  36 <p class="p5">a = [1, 2, 3];</p>
  37 <p class="p5">x = <span class="s3">RefCopy</span>(a);</p>
  38 <p class="p5">b = x.next;</p>
  39 <p class="p5">b.put(0, 100); <span class="s4">// modify b</span></p>
  40 <p class="p3"><span class="s5">a; </span>// a is unchanged.</p>
  41 </body>
  42 </html>