archived-doc-pt-br/reference/classobj/reference.xml

<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.2 $ -->
 <reference id="ref.classobj">
  <title>Fun&ccedil;&otilde;es Class/Object </title>
  <titleabbrev>Classes/Objetos</titleabbrev>

  <partintro>
    <section id="classobj.intro">
     &reftitle.intro;
     <para>
      Estas fun&ccedil;&otilde;es te permitem obter informa&ccedil;&otilde;es sobre classes e inst&acirc;ncias 
	  de objetos. Voc&ecirc; pode obter o nome da classe que um objeto pertence,
	  bem como suas propriedades e m&eacute;todos. Usando estas fun&ccedil;&otilde;es, voc&ecirc; pode
	  descobrir n&atilde;o apenas a classe de um objeto, mas tamb&eacute;m seu parentesco
	  (i.e. Qual classe o objeto se extende).
     </para>
    </section>
    <section id="classobj.examples">
     &reftitle.examples;
     <para>
      Neste exemplo, n&oacute;s primeiramente definiremos uma classe base
	  e uma extens&atilde;o da classe. A classe base descreve um vegetal comum, 
	  que &eacute; comest&iacute;vel ou n&atilde;o e que tem sua cor. A sub-classe<varname>Espinafre</varname>
	  adiciona um m&eacute;todo para cozinh&aacute;-lo e outro para descobrir se ele est&aacute; cozido.
     </para>
     <para>
      <example>
       <title>classes.inc</title>
       <programlisting role="php">
<![CDATA[
<?php

// base class with member properties and methods
class Vegetable {

    var $edible;
    var $color;

    function Vegetable( $edible, $color="green" ) {
        $this->edible = $edible;
        $this->color = $color;
    }

    function is_edible() {
        return $this->edible;
    }

    function what_color() {
        return $this->color;
    }
    
} // end of class Vegetable

// extends the base class
class Spinach extends Vegetable {

    var $cooked = false;

    function Spinach() {
        $this->Vegetable( true, "green" );
    }

    function cook_it() {
        $this->cooked = true;
    }

    function is_cooked() {
        return $this->cooked;
    }
    
} // end of class Spinach

?>
]]>
       </programlisting>
      </example>
     </para>
     <para>
     N&oacute;s inst&acirc;nciamos 2 objetos destas classes e exibimos informa&ccedil;&otilde;es sobre elas, 
	 incluindo o parentesco de suas classes.
     N&oacute;s tamb&eacute;m definimos algumas fun&ccedil;&otilde;es &uacute;teis, principalmente ter uma boa s&aacute;ida de
	 vari&aacute;veis. 
     </para>
     <para>
      <example>
       <title>test_script.php</title>
       <programlisting role="php">
<![CDATA[
<pre>
<?php

include "classes.inc";

// utility functions

function print_vars($obj) {
    $arr = get_object_vars($obj);
    while (list($prop, $val) = each($arr))
        echo "\t$prop = $val\n";
}

function print_methods($obj) {
    $arr = get_class_methods(get_class($obj));
    foreach ($arr as $method)
        echo "\tfunction $method()\n";
}

function class_parentage($obj, $class) {
    global $$obj;
    if (is_subclass_of($$obj, $class)) {
        echo "Object $obj belongs to class ".get_class($$obj);
        echo " a subclass of $class\n";
    } else {
        echo "Object $obj does not belong to a subclass of $class\n";
    }
}

// instantiate 2 objects

$veggie = new Vegetable(true,"blue");
$leafy = new Spinach();

// print out information about objects
echo "veggie: CLASS ".get_class($veggie)."\n";
echo "leafy: CLASS ".get_class($leafy);
echo ", PARENT ".get_parent_class($leafy)."\n";

// show veggie properties
echo "\nveggie: Properties\n";
print_vars($veggie);

// and leafy methods
echo "\nleafy: Methods\n";
print_methods($leafy);

echo "\nParentage:\n";
class_parentage("leafy", "Spinach");
class_parentage("leafy", "Vegetable");
?>
</pre>
]]>
       </programlisting>
      </example>
     </para>
     <para>
      Uma coisa importante para notar no exemplo acima &eacute que o 
	  objeto<varname>$leafy</varname> &eacute uma inst&acirc;ncia da 
	  classe<classname>Espinafre</classname> que &eacute uma subclasse 
	  de <classname>Vegetal</classname>,
      ent&atilde;o a &uacute;ltima parte do script acima retornar&aacute:
     </para>
     <para>
      <informalexample>
       <programlisting>
<![CDATA[
       [...]
Parentage:
Object leafy does not belong to a subclass of Spinach
Object leafy belongs to class spinach a subclass of Vegetable
]]>
       </programlisting>
      </informalexample>
     </para>
    </section>
  </partintro>

&reference.classobj.functions;

 </reference>
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