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>Capítulo 19. Classes e Objetos (PHP 5)</TD
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><A
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>Iteração de Objetos</A
></H1
><P
>
PHP 5 fornece uma maneira de defini objetos para que seja possível
iterar por uma lista de items, com, por exeplo, uma instrução <A
HREF="control-structures.foreach.html"
>a seção <I
><TT
CLASS="literal"
>foreach</TT
></I
> Capítulo 16</A
> . Por padrão, todas as
propriedades <A
HREF="language.oop5.visibility.html"
>visíveis</A
> serão
usadas para a iteração.
</P
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><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN5833"
></A
><P
><B
>Exemplo 19-21. Simple Object Iteration</B
></P
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><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">MyClass<br /></font><font color="#007700">{<br /> </font><font color="#0000BB">public $var1 </font><font color="#007700">= </font><font color="#DD0000">'value 1'</font><font color="#007700">;<br /> </font><font color="#0000BB">public $var2 </font><font color="#007700">= </font><font color="#DD0000">'value 2'</font><font color="#007700">;<br /> </font><font color="#0000BB">public $var3 </font><font color="#007700">= </font><font color="#DD0000">'value 3'</font><font color="#007700">;<br /><br /> </font><font color="#0000BB">protected $protected </font><font color="#007700">= </font><font color="#DD0000">'protected var'</font><font color="#007700">;<br /> </font><font color="#0000BB">private $private </font><font color="#007700">= </font><font color="#DD0000">'private var'</font><font color="#007700">;<br /><br /> function </font><font color="#0000BB">iterateVisible</font><font color="#007700">() {<br /> echo </font><font color="#DD0000">"MyClass::iterateVisible:\n"</font><font color="#007700">;<br /> foreach(</font><font color="#0000BB">$this </font><font color="#007700">as </font><font color="#0000BB">$key </font><font color="#007700">=> </font><font color="#0000BB">$value</font><font color="#007700">) {<br /> print </font><font color="#DD0000">"$key => $value</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /> }<br /> }<br />}<br /><br /></font><font color="#0000BB">$class </font><font color="#007700">= new </font><font color="#0000BB">MyClass</font><font color="#007700">();<br /><br />foreach(</font><font color="#0000BB">$class </font><font color="#007700">as </font><font color="#0000BB">$key </font><font color="#007700">=> </font><font color="#0000BB">$value</font><font color="#007700">) {<br /> print </font><font color="#DD0000">"$key => $value</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br />}<br />echo </font><font color="#DD0000">"\n"</font><font color="#007700">;<br /><br /><br /></font><font color="#0000BB">$class</font><font color="#007700">-></font><font color="#0000BB">iterateVisible</font><font color="#007700">();<br /><br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
><P
>O exemplo acima irá imprimir:</P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
var1 => value 1<br />var2 => value 2<br />var3 => value 3<br /><br />MyClass::iterateVisible:<br />var1 => value 1<br />var2 => value 2<br />var3 => value 3<br />protected => protected var<br />private => private var</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> Como a saída mostra, o <A
HREF="control-structures.foreach.html"
>foreach</A
> iteragiu por cada uma
das variáveis <A
HREF="language.oop5.visibility.html"
>visíveis</A
> que podem ser
acessadas. Indo um pouco mais longe, você pode
<CODE
CLASS="varname"
>implementar</CODE
> uma das <A
HREF="language.oop5.interfaces.html"
>interfaces</A
> internas do PHP5 chamada
<CODE
CLASS="varname"
>Iterator</CODE
>. Isso permite que o objeto decida o que
e como o objeto será iterado.
</P
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CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN5844"
></A
><P
><B
>Exemplo 19-22. Iteração de Objeto implmentando Iterator</B
></P
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><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">MyIterator implements Iterator<br /></font><font color="#007700">{<br /> </font><font color="#0000BB">private $var </font><font color="#007700">= array();<br /><br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">__construct</font><font color="#007700">(</font><font color="#0000BB">$array</font><font color="#007700">)<br /> {<br /> if (</font><font color="#0000BB">is_array</font><font color="#007700">(</font><font color="#0000BB">$array</font><font color="#007700">) ) {<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">var </font><font color="#007700">= </font><font color="#0000BB">$array</font><font color="#007700">;<br /> }<br /> }<br /><br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">rewind</font><font color="#007700">() {<br /> echo </font><font color="#DD0000">"rewinding\n"</font><font color="#007700">;<br /> </font><font color="#0000BB">reset</font><font color="#007700">(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">var</font><font color="#007700">);<br /> }<br /><br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">current</font><font color="#007700">() {<br /> </font><font color="#0000BB">$var </font><font color="#007700">= </font><font color="#0000BB">current</font><font color="#007700">(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">var</font><font color="#007700">);<br /> echo </font><font color="#DD0000">"current: $var</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /> return </font><font color="#0000BB">$var</font><font color="#007700">;<br /> }<br /><br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">key</font><font color="#007700">() {<br /> </font><font color="#0000BB">$var </font><font color="#007700">= </font><font color="#0000BB">key</font><font color="#007700">(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">var</font><font color="#007700">);<br /> echo </font><font color="#DD0000">"key: $var</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /> return </font><font color="#0000BB">$var</font><font color="#007700">;<br /> }<br /><br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">next</font><font color="#007700">() {<br /> </font><font color="#0000BB">$var </font><font color="#007700">= </font><font color="#0000BB">next</font><font color="#007700">(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">var</font><font color="#007700">);<br /> echo </font><font color="#DD0000">"next: $var</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /> return </font><font color="#0000BB">$var</font><font color="#007700">;<br /> }<br /><br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">valid</font><font color="#007700">() {<br /> </font><font color="#0000BB">$var </font><font color="#007700">= </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">current</font><font color="#007700">() !== </font><font color="#0000BB">false</font><font color="#007700">;<br /> echo </font><font color="#DD0000">"valid: </font><font color="#007700">{</font><font color="#DD0000">$var</font><font color="#007700">}\n</font><font color="#DD0000">"</font><font color="#007700">;<br /> return </font><font color="#0000BB">$var</font><font color="#007700">;<br /> }<br />}<br /><br /></font><font color="#0000BB">$values </font><font color="#007700">= array(</font><font color="#0000BB">1</font><font color="#007700">,</font><font color="#0000BB">2</font><font color="#007700">,</font><font color="#0000BB">3</font><font color="#007700">);<br /></font><font color="#0000BB">$it </font><font color="#007700">= new </font><font color="#0000BB">MyIterator</font><font color="#007700">(</font><font color="#0000BB">$values</font><font color="#007700">);<br /><br />foreach (</font><font color="#0000BB">$it </font><font color="#007700">as </font><font color="#0000BB">$a </font><font color="#007700">=> </font><font color="#0000BB">$b</font><font color="#007700">) {<br /> print </font><font color="#DD0000">"$a: $b</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br />}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
><P
>O exemplo acima irá imprimir:</P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
rewinding<br />current: 1<br />valid: 1<br />current: 1<br />key: 0<br />0: 1<br />next: 2<br />current: 2<br />valid: 1<br />current: 2<br />key: 1<br />1: 2<br />next: 3<br />current: 3<br />valid: 1<br />current: 3<br />key: 2<br />2: 3<br />next:<br />current:<br />valid:</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> Você também pode definir sua classe para que ela não tenha que definir
todas as funções do <CODE
CLASS="varname"
>Iterator</CODE
> simplesmente implementado
a interface <CODE
CLASS="varname"
>IteratorAggregate</CODE
> do PHP 5.
</P
><TABLE
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CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN5852"
></A
><P
><B
>Exemplo 19-23. Iteração de Objeto implementado IteratorAggregate</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
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><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">MyCollection implements IteratorAggregate </font><font color="#007700">{<br /> </font><font color="#0000BB">private $items </font><font color="#007700">= array();<br /> </font><font color="#0000BB">private $count </font><font color="#007700">= </font><font color="#0000BB">0</font><font color="#007700">;<br /><br /> </font><font color="#FF8000">/* Definião requirida da interface IteratorAggregate */<br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">getIterator</font><font color="#007700">() {<br /> return new </font><font color="#0000BB">MyIterator</font><font color="#007700">(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">items</font><font color="#007700">);<br /> }<br /><br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">add</font><font color="#007700">(</font><font color="#0000BB">$value</font><font color="#007700">) {<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">items</font><font color="#007700">[</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">count</font><font color="#007700">++] = </font><font color="#0000BB">$value</font><font color="#007700">;<br /> }<br /><br />}<br /><br /></font><font color="#0000BB">$coll </font><font color="#007700">= new </font><font color="#0000BB">MyCollection</font><font color="#007700">();<br /></font><font color="#0000BB">$coll</font><font color="#007700">-></font><font color="#0000BB">add</font><font color="#007700">(</font><font color="#DD0000">'value 1'</font><font color="#007700">);<br /></font><font color="#0000BB">$coll</font><font color="#007700">-></font><font color="#0000BB">add</font><font color="#007700">(</font><font color="#DD0000">'value 2'</font><font color="#007700">);<br /></font><font color="#0000BB">$coll</font><font color="#007700">-></font><font color="#0000BB">add</font><font color="#007700">(</font><font color="#DD0000">'value 3'</font><font color="#007700">);<br /><br />foreach (</font><font color="#0000BB">$coll </font><font color="#007700">as </font><font color="#0000BB">$key </font><font color="#007700">=> </font><font color="#0000BB">$val</font><font color="#007700">) {<br /> echo </font><font color="#DD0000">"key/value: </font><font color="#007700">[</font><font color="#DD0000">$key -> $val</font><font color="#007700">]\n\n</font><font color="#DD0000">"</font><font color="#007700">;<br />}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
><P
>O exemplo acima irá imprimir:</P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
rewinding<br />current: value 1<br />valid: 1<br />current: value 1<br />key: 0<br />key/value: [0 -> value 1]<br /><br />next: value 2<br />current: value 2<br />valid: 1<br />current: value 2<br />key: 1<br />key/value: [1 -> value 2]<br /><br />next: value 3<br />current: value 3<br />valid: 1<br />current: value 3<br />key: 2<br />key/value: [2 -> value 3]<br /><br />next:<br />current:<br />valid:</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Nota: </B
>
Para mais exemplos de iteração, veja a
<A
HREF="ref.spl.html"
>Extensão SPL</A
>.
</P
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