我不是PHP开发人员，所以我想知道在PHP中使用显式getter/setter的优点和缺点是什么，在纯OOP风格中，带有私有字段(我喜欢的方式):
class MyClass {
private $firstField;
private $secondField;
public function getFirstField() {
return $this->firstField;
}
public function setFirstField($x) {
$this->firstField = $x;
}
public function getSecondField() {
return $this->secondField;
}
public function setSecondField($x) {
$this->secondField = $x;
}
}
或者只是公共字段:
class MyClass {
public $firstField;
public $secondField;
}
封装在任何面向对象语言中都很重要，与受欢迎程度无关。在动态类型语言(如PHP)中，它特别有用，因为如果不使用设置符，几乎没有办法确保属性是特定类型的。
在PHP中，这是有效的:
class Foo {
public $bar; // should be an integer
}
$foo = new Foo;
$foo->bar = "string";
在Java中，它没有:
class Foo {
public int bar;
}
Foo myFoo = new Foo();
myFoo.bar = "string"; // error
使用魔法方法(__get和__set)也可以，但只有当访问的属性的可见性低于当前作用域可以访问的时候。如果使用不当，调试时很容易让您头疼。
封装在任何面向对象语言中都很重要，与受欢迎程度无关。在动态类型语言(如PHP)中，它特别有用，因为如果不使用设置符，几乎没有办法确保属性是特定类型的。
在PHP中，这是有效的:
class Foo {
public $bar; // should be an integer
}
$foo = new Foo;
$foo->bar = "string";
在Java中，它没有:
class Foo {
public int bar;
}
Foo myFoo = new Foo();
myFoo.bar = "string"; // error
使用魔法方法(__get和__set)也可以，但只有当访问的属性的可见性低于当前作用域可以访问的时候。如果使用不当，调试时很容易让您头疼。
在阅读了其他建议后，我倾向于这样说:
作为GENERIC规则，你不会总是为所有属性定义setter，特别是“内部”属性(信号量、内部标志……)。只读属性显然没有setter，所以有些属性只有getter;这就是__get()缩小代码的地方:
define a __get() (magical global getters) for all those properties which are alike,
group them in arrays so:
they'll share common characteristics: monetary values will/may come up properly formatted, dates in an specific layout (ISO, US, Intl.), etc.
the code itself can verify that only existing & allowed properties are being read using this magical method.
whenever you need to create a new similar property, just declare it and add its name to the proper array and it's done. That's way FASTER than defining a new getter, perhaps with some lines of code REPEATED again and again all over the class code.
是的!我们也可以写一个私有方法来做到这一点，但话又说回来，我们将声明许多方法(++内存)，最终调用另一个总是相同的方法。为什么不写一个单一的方法来管理它们呢?(是的!双关语!)):
Magic setter也可以只响应特定的属性，因此可以单独在一个方法中筛选所有日期类型属性的无效值。如果日期类型属性列在数组中，则可以轻松定义它们的setter。当然，这只是一个例子。有太多的情况。
About readability... Well... That's another debate: I don't like to be bound to the uses of an IDE (in fact, I don't use them, they tend to tell me (and force me) how to write... and I have my likes about coding "beauty"). I tend to be consistent about naming, so using ctags and a couple of other aids is sufficient to me... Anyway: once all this magic setters and getters are done, I write the other setters that are too specific or "special" to be generalized in a __set() method. And that covers all I need about getting and setting properties. Of course: there's not always a common ground, or there are such a few properties that is not worth the trouble of coding a magical method, and then there's still the old good traditional setter/getter pair.
编程语言就是人类的人工语言。因此，它们都有自己的语调或重音、语法和风格，所以我不会假装用与Java或c#相同的“重音”来编写Ruby或Python代码，也不会编写类似Perl或SQL的JavaScript或PHP……用他们该用的方式去使用他们。
Well, PHP does have magic methods __get, __set, __isset & __unset, which is always a start. Alas proper (get it?) OO properties is more than magic methods. The main problem with PHP's implementation is that magic methods are called for all inaccessible properties. Which means you have to Repeat Yourself (eg. by calling property_exists()) in the magic methods when determining if name is actually a property of your object. And you can't really solve this general problem with a base class unless all your classes inherit from ie. ClassWithProperties, since PHP lacks multiple inheritance.
相比之下，Python的新样式类提供了property()，它允许显式地定义所有属性。c#有特殊的语法。
http://en.wikipedia.org/wiki/Property_(编程)
