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>Capítulo 19. Classes e Objetos (PHP 5)</TD
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><H1
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><A
NAME="language.oop5.overloading"
>Sobrecarga</A
></H1
><P
> Tanto chamada de métodos e acesso a membros podem ser sobrecarregados pelos métodos
__call, __get e __set. Esses métodos só serão
disparados quando seu objeto ou o objeto herdado não contiver o
membro ou método que você está tentando acessar.
Todos os métodos sobrecarregados devem ser definidos
<A
HREF="language.oop5.visibility.html"
>estáticos</A
>.
</P
><P
> A partir do PHP 5.1.0 também é possível sobrecarregar as
funções <A
HREF="function.isset.html"
><B
CLASS="function"
>isset()</B
></A
> and <A
HREF="function.unset.html"
><B
CLASS="function"
>unset()</B
></A
> através
dos métodos __isset e __unset respectivamente.
</P
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="language.oop5.overloading.members"
>Sobrecarga de membros</A
></H2
>void <B
CLASS="methodname"
>__set</B
> ( string name, mixed value )<BR
></BR
>mixed <B
CLASS="methodname"
>__get</B
> ( string name )<BR
></BR
>bool <B
CLASS="methodname"
>__isset</B
> ( string name )<BR
></BR
>void <B
CLASS="methodname"
>__unset</B
> ( string name )<BR
></BR
><P
> Membros de classes podem ser sobrecarregados para executar código específico definido
na sua classe definindo esses métodos especialmente nomeados. O parâmetro <CODE
CLASS="varname"
>$name</CODE
>
usado é o nome da variável que deve ser configurada ou recuperada.
O parâmetro <CODE
CLASS="varname"
>$value</CODE
> do método __set() especifica o
valor que o objeto deve atribuir à variável <CODE
CLASS="varname"
>$name</CODE
>.
</P
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><A
NAME="AEN5804"
></A
><P
><B
>Exemplo 19-19. Exemplo de sobrecarga com __get, __set, __isset e __unset</B
></P
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><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Setter<br /></font><font color="#007700">{<br /> </font><font color="#0000BB">public $n</font><font color="#007700">;<br /> </font><font color="#0000BB">private $x </font><font color="#007700">= array(</font><font color="#DD0000">"a" </font><font color="#007700">=> </font><font color="#0000BB">1</font><font color="#007700">, </font><font color="#DD0000">"b" </font><font color="#007700">=> </font><font color="#0000BB">2</font><font color="#007700">, </font><font color="#DD0000">"c" </font><font color="#007700">=> </font><font color="#0000BB">3</font><font color="#007700">);<br /><br /> </font><font color="#0000BB">private </font><font color="#007700">function </font><font color="#0000BB">__get</font><font color="#007700">(</font><font color="#0000BB">$nm</font><font color="#007700">)<br /> {<br /> echo </font><font color="#DD0000">"Getting </font><font color="#007700">[</font><font color="#DD0000">$nm</font><font color="#007700">]\n</font><font color="#DD0000">"</font><font color="#007700">;<br /><br /> if (isset(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">[</font><font color="#0000BB">$nm</font><font color="#007700">])) {<br /> </font><font color="#0000BB">$r </font><font color="#007700">= </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">[</font><font color="#0000BB">$nm</font><font color="#007700">];<br /> print </font><font color="#DD0000">"Returning: $r</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /> return </font><font color="#0000BB">$r</font><font color="#007700">;<br /> } else {<br /> echo </font><font color="#DD0000">"Nothing!\n"</font><font color="#007700">;<br /> }<br /> }<br /><br /> </font><font color="#0000BB">private </font><font color="#007700">function </font><font color="#0000BB">__set</font><font color="#007700">(</font><font color="#0000BB">$nm</font><font color="#007700">, </font><font color="#0000BB">$val</font><font color="#007700">)<br /> {<br /> echo </font><font color="#DD0000">"Setting </font><font color="#007700">[</font><font color="#DD0000">$nm</font><font color="#007700">]</font><font color="#DD0000"> to $val</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /><br /> if (isset(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">[</font><font color="#0000BB">$nm</font><font color="#007700">])) {<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">[</font><font color="#0000BB">$nm</font><font color="#007700">] = </font><font color="#0000BB">$val</font><font color="#007700">;<br /> echo </font><font color="#DD0000">"OK!\n"</font><font color="#007700">;<br /> } else {<br /> echo </font><font color="#DD0000">"Not OK!\n"</font><font color="#007700">;<br /> }<br /> }<br /><br /> </font><font color="#0000BB">private </font><font color="#007700">function </font><font color="#0000BB">__isset</font><font color="#007700">(</font><font color="#0000BB">$nm</font><font color="#007700">)<br /> {<br /> echo </font><font color="#DD0000">"Checking if $nm is set</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /><br /> return isset(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">[</font><font color="#0000BB">$nm</font><font color="#007700">]);<br /> }<br /><br /> </font><font color="#0000BB">private </font><font color="#007700">function </font><font color="#0000BB">__unset</font><font color="#007700">(</font><font color="#0000BB">$nm</font><font color="#007700">)<br /> {<br /> echo </font><font color="#DD0000">"Unsetting $nm</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /><br /> unset(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">[</font><font color="#0000BB">$nm</font><font color="#007700">]);<br /> }<br />}<br /><br /></font><font color="#0000BB">$foo </font><font color="#007700">= new </font><font color="#0000BB">Setter</font><font color="#007700">();<br /></font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">n </font><font color="#007700">= </font><font color="#0000BB">1</font><font color="#007700">;<br /></font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">a </font><font color="#007700">= </font><font color="#0000BB">100</font><font color="#007700">;<br /></font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">a</font><font color="#007700">++;<br /></font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">z</font><font color="#007700">++;<br /><br /></font><font color="#0000BB">var_dump</font><font color="#007700">(isset(</font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">a</font><font color="#007700">)); </font><font color="#FF8000">//true<br /></font><font color="#007700">unset(</font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">a</font><font color="#007700">);<br /></font><font color="#0000BB">var_dump</font><font color="#007700">(isset(</font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">a</font><font color="#007700">)); </font><font color="#FF8000">//false<br /><br />// Isso não passa pelo método __isset()<br />// porque 'n' é uma proriedade pública<br /></font><font color="#0000BB">var_dump</font><font color="#007700">(isset(</font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">n</font><font color="#007700">));<br /><br /></font><font color="#0000BB">var_dump</font><font color="#007700">(</font><font color="#0000BB">$foo</font><font color="#007700">);<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
><P
>O exemplo acima irá imprimir:</P
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><TR
><TD
><code><font color="#000000">
Setting [a] to 100<br />OK!<br />Getting [a]<br />Returning: 100<br />Setting [a] to 101<br />OK!<br />Getting [z]<br />Nothing!<br />Setting [z] to 1<br />Not OK!<br /><br />Checking if a is set<br />bool(true)<br />Unsetting a<br />Checking if a is set<br />bool(false)<br />bool(true)<br /><br />object(Setter)#1 (2) {<br /> ["n"]=><br /> int(1)<br /> ["x:private"]=><br /> array(2) {<br /> ["b"]=><br /> int(2)<br /> ["c"]=><br /> int(3)<br /> }<br />}</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="language.oop5.overloading.methods"
>Sobrecarga de método</A
></H2
>mixed <B
CLASS="methodname"
>__call</B
> ( string name, array arguments )<BR
></BR
><P
> Membros de classes podem ser sobrecarregados para executar código específico definido
na sua classe definindo esses métodos especialmente nomeados. O parâmetro
<CODE
CLASS="varname"
>$name</CODE
> usado é o nome da função que foi requerida
a ser usada. Os argumentos que foram passado na função serão definidos
como um array no parâmetro <CODE
CLASS="varname"
>$arguments</CODE
>.
O valor retorna do método __call() será retornado ao
chamador do método.
</P
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CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN5823"
></A
><P
><B
>Exemplo 19-20. Exemplo de sobrecarga com __call</B
></P
><TABLE
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><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Caller<br /></font><font color="#007700">{<br /> </font><font color="#0000BB">private $x </font><font color="#007700">= array(</font><font color="#0000BB">1</font><font color="#007700">, </font><font color="#0000BB">2</font><font color="#007700">, </font><font color="#0000BB">3</font><font color="#007700">);<br /><br /> function </font><font color="#0000BB">__call</font><font color="#007700">(</font><font color="#0000BB">$m</font><font color="#007700">, </font><font color="#0000BB">$a</font><font color="#007700">)<br /> {<br /> print </font><font color="#DD0000">"Método $m chamado:</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /> </font><font color="#0000BB">var_dump</font><font color="#007700">(</font><font color="#0000BB">$a</font><font color="#007700">);<br /> return </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">;<br /> }<br />}<br /><br /></font><font color="#0000BB">$foo </font><font color="#007700">= new </font><font color="#0000BB">Caller</font><font color="#007700">();<br /></font><font color="#0000BB">$a </font><font color="#007700">= </font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">teste</font><font color="#007700">(</font><font color="#0000BB">1</font><font color="#007700">, </font><font color="#DD0000">"2"</font><font color="#007700">, </font><font color="#0000BB">3.4</font><font color="#007700">, </font><font color="#0000BB">true</font><font color="#007700">);<br /></font><font color="#0000BB">var_dump</font><font color="#007700">(</font><font color="#0000BB">$a</font><font color="#007700">);<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
><P
>O exemplo acima irá imprimir:</P
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><TD
><code><font color="#000000">
Método teste chamado:<br />array(4) {<br /> [0]=><br /> int(1)<br /> [1]=><br /> string(1) "2"<br /> [2]=><br /> float(3.4)<br /> [3]=><br /> bool(true)<br />}<br />array(3) {<br /> [0]=><br /> int(1)<br /> [1]=><br /> int(2)<br /> [2]=><br /> int(3)<br />}</font>
</code></TD
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