mingw/html/lib/Tie/Scalar.html

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  13 <big><strong><span class="block">&nbsp;Tie::StdScalar - base class definitions for tied scalars</span></strong></big>
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  20 <ul>
  21
  22         <li><a href="#name">NAME</a></li>
  23         <li><a href="#synopsis">SYNOPSIS</a></li>
  24         <li><a href="#description">DESCRIPTION</a></li>
  25         <li><a href="#more_information">MORE INFORMATION</a></li>
  26 </ul>
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  30 <p>
  31 </p>
  32 <h1><a name="name">NAME</a></h1>
  33 <p>Tie::Scalar, Tie::StdScalar - base class definitions for tied scalars</p>
  34 <p>
  35 </p>
  36 <hr />
  37 <h1><a name="synopsis">SYNOPSIS</a></h1>
  38 <pre>
  39     package NewScalar;
  40     require Tie::Scalar;</pre>
  41 <pre>
  42     @ISA = (Tie::Scalar);</pre>
  43 <pre>
  44     sub FETCH { ... }           # Provide a needed method
  45     sub TIESCALAR { ... }       # Overrides inherited method</pre>
  46 <pre>
  47     package NewStdScalar;
  48     require Tie::Scalar;</pre>
  49 <pre>
  50     @ISA = (Tie::StdScalar);</pre>
  51 <pre>
  52     # All methods provided by default, so define only what needs be overridden
  53     sub FETCH { ... }</pre>
  54 <pre>
  55     package main;</pre>
  56 <pre>
  57     tie $new_scalar, 'NewScalar';
  58     tie $new_std_scalar, 'NewStdScalar';</pre>
  59 <p>
  60 </p>
  61 <hr />
  62 <h1><a name="description">DESCRIPTION</a></h1>
  63 <p>This module provides some skeletal methods for scalar-tying classes. See
  64 <a href="file://C|\msysgit\mingw\html/pod/perltie.html">the perltie manpage</a> for a list of the functions required in tying a scalar to a
  65 package. The basic <strong>Tie::Scalar</strong> package provides a <code>new</code> method, as well
  66 as methods <code>TIESCALAR</code>, <code>FETCH</code> and <code>STORE</code>. The <strong>Tie::StdScalar</strong>
  67 package provides all the methods specified in  <a href="file://C|\msysgit\mingw\html/pod/perltie.html">the perltie manpage</a>. It inherits from
  68 <strong>Tie::Scalar</strong> and causes scalars tied to it to behave exactly like the
  69 built-in scalars, allowing for selective overloading of methods. The <code>new</code>
  70 method is provided as a means of grandfathering, for classes that forget to
  71 provide their own <code>TIESCALAR</code> method.</p>
  72 <p>For developers wishing to write their own tied-scalar classes, the methods
  73 are summarized below. The <a href="file://C|\msysgit\mingw\html/pod/perltie.html">the perltie manpage</a> section not only documents these, but
  74 has sample code as well:</p>
  75 <dl>
  76 <dt><strong><a name="item_tiescalar_classname_2c_list">TIESCALAR classname, LIST</a></strong>
  77
  78 <dd>
  79 <p>The method invoked by the command <code>tie $scalar, classname</code>. Associates a new
  80 scalar instance with the specified class. <code>LIST</code> would represent additional
  81 arguments (along the lines of <a href="file://C|\msysgit\mingw\html/lib/AnyDBM_File.html">the AnyDBM_File manpage</a> and compatriots) needed to
  82 complete the association.</p>
  83 </dd>
  84 </li>
  85 <dt><strong><a name="item_fetch_this">FETCH this</a></strong>
  86
  87 <dd>
  88 <p>Retrieve the value of the tied scalar referenced by <em>this</em>.</p>
  89 </dd>
  90 </li>
  91 <dt><strong><a name="item_store_this_2c_value">STORE this, value</a></strong>
  92
  93 <dd>
  94 <p>Store data <em>value</em> in the tied scalar referenced by <em>this</em>.</p>
  95 </dd>
  96 </li>
  97 <dt><strong><a name="item_destroy_this">DESTROY this</a></strong>
  98
  99 <dd>
 100 <p>Free the storage associated with the tied scalar referenced by <em>this</em>.
 101 This is rarely needed, as Perl manages its memory quite well. But the
 102 option exists, should a class wish to perform specific actions upon the
 103 destruction of an instance.</p>
 104 </dd>
 105 </li>
 106 </dl>
 107 <p>
 108 </p>
 109 <hr />
 110 <h1><a name="more_information">MORE INFORMATION</a></h1>
 111 <p>The <a href="file://C|\msysgit\mingw\html/pod/perltie.html">the perltie manpage</a> section uses a good example of tying scalars by associating
 112 process IDs with priority.</p>
 113 <table border="0" width="100%" cellspacing="0" cellpadding="3">
 114 <tr><td class="block" style="background-color: #cccccc" valign="middle">
 115 <big><strong><span class="block">&nbsp;Tie::StdScalar - base class definitions for tied scalars</span></strong></big>
 116 </td></tr>
 117 </table>
 118
 119 </body>
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