带参数的 PHP 构造函数
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PHP constructor with a parameter
提问by Kamil
I need a function that will do something like this:
我需要一个函数来做这样的事情：
$arr = array(); // This is the array where I'm storing data
$f = new MyRecord(); // I have __constructor in class Field() that sets some default values
$f->{'fid'} = 1;
$f->{'fvalue-string'} = $_POST['data'];
$arr[] = $f;
$f = new Field();
$f->{'fid'} = 2;
$f->{'fvalue-int'} = $_POST['data2'];
$arr[] = $f;
When I write something like this:
当我写这样的东西时：
$f = new Field(1, 'fvalue-string', $_POST['data-string'], $arr);
$f = new Field(2, 'fvalue-int', $_POST['data-integer'], $arr);
// Description of parameters that I want to use:
// 1 - always integer, unique (fid property of MyRecord class)
// 'fvalue-int' - name of field/property in MyRecord class where the next parameter will go
// 3. Data for field specified in the previous parameter
// 4. Array where the class should go
I don't know how to make a parametrized constructor in PHP.
我不知道如何在 PHP 中创建参数化构造函数。
Now I use a constructor like this:
现在我使用这样的构造函数：
class MyRecord
{
function __construct() {
$default = new stdClass();
$default->{'fvalue-string'} = '';
$default->{'fvalue-int'} = 0;
$default->{'fvalue-float'} = 0;
$default->{'fvalue-image'} = ' ';
$default->{'fvalue-datetime'} = 0;
$default->{'fvalue-boolean'} = false;
$this = $default;
}
}
回答by Mike B
Read all of Constructors and Destructors.
阅读所有构造函数和析构函数。
Constructors can take parameters like any other function or method in PHP:
构造函数可以像 PHP 中的任何其他函数或方法一样接受参数：
class MyClass {
public $param;
public function __construct($param) {
$this->param = $param;
}
}
$myClass = new MyClass('foobar');
echo $myClass->param; // foobar
Your example of how you use constructors now won't even compile as you can't reassign $this.
您现在如何使用构造函数的示例甚至无法编译，因为您无法重新分配$this.
Also, you don't need the curly brackets every time you access or set a property. $object->propertyworks just fine. You only need to use curly-brackets under special circumstances like if you need to evaluate a method $object->{$foo->bar()} = 'test';
此外，每次访问或设置属性时都不需要大括号。$object->property工作得很好。你只需要在特殊情况下使用花括号，比如你需要评估一个方法$object->{$foo->bar()} = 'test';
回答by Michael Robinson
If you want to pass an array as a parameter and 'auto' populate your properties:
如果要将数组作为参数传递并“自动”填充属性：
class MyRecord {
function __construct($parameters = array()) {
foreach($parameters as $key => $value) {
$this->$key = $value;
}
}
}
Notice that a constructor is used to create & initialize an object, therefore one may use $thisto use / modify the object you're constructing.
请注意，构造函数用于创建和初始化对象，因此可以$this使用/修改您正在构造的对象。
