php 如何“回声”一个班级？
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How to "echo" a class?
提问by Andrew
This is probably really easy but I can't seem to figure out how to print/echo a class so I can find out some details about it.
这可能真的很容易，但我似乎无法弄清楚如何打印/回显类，因此我可以找到有关它的一些详细信息。
I know this doesn't work, but this is what I'm trying to do:
我知道这行不通，但这就是我想要做的：
<?php echo $class; ?>
What is the correct way to achieve something like this?
实现这样的目标的正确方法是什么？
回答by David Snabel-Caunt
You could try adding a toStringmethod to your class. You can then echo some useful information, or call a render method to generate HTML or something!
您可以尝试在您的类中添加一个toString方法。然后就可以回显一些有用的信息，或者调用一个render方法来生成HTML什么的！
The __toString method is called when you do something like the following:
__toString 方法在您执行以下操作时被调用：
echo $class;
or
或者
$str = (string)$class;
The example linked is as follows:
链接的例子如下：
<?php
// Declare a simple class
class TestClass
{
public $foo;
public function __construct($foo) {
$this->foo = $foo;
}
public function __toString() {
return $this->foo;
}
}
$class = new TestClass('Hello');
echo $class;
?>
回答by James McNellis
回答by Luc M
Use var_dump on an instance of your class.
在类的实例上使用 var_dump。
<?php
$my_class = new SomeClass();
var_dump( $my_class );
?>
回答by user24601
To get more detailed info out of your class (if you want to know what's available to a child class for example), you can add a debug()method.
要从您的类中获取更详细的信息（例如，如果您想知道子类可以使用什么），您可以添加一个debug()方法。
Here's an example class with such a method that I use that prints out the methods, default vars, and instance vars in a nice structured way:
这是一个示例类，我使用它以一种很好的结构化方式打印出方法、默认变量和实例变量：
<?php
class TestClass{
private $privateVar = 'Default private';
protected $protectedVar = 'Default protected';
public $publicVar = 'Default public';
public function __construct(){
$this->privateVar = 'parent instance';
}
public function test(){}
/**
* Prints out detailed info of the class and instance.
*/
public function debug(){
$class = __CLASS__;
echo "<pre>$class Methods:\n";
var_dump(get_class_methods($class));
echo "\n\n$class Default Vars:\n";
var_dump(get_class_vars($class));
echo "\n\n$class Current Vars:\n";
var_dump($this);
echo "</pre>";
}
}
class TestClassChild extends TestClass{
public function __construct(){
$this->privateVar = 'child instance';
}
}
$test = new TestClass();
$test2 = new TestClassChild();
$test->debug();
$test2->debug();
回答by Alexander Sholk
You can use Symfony VarDumper Component http://symfony.com/doc/current/components/var_dumper/introduction.html:
您可以使用 Symfony VarDumper 组件http://symfony.com/doc/current/components/var_dumper/introduction.html：
Install it via Composer:
通过 Composer 安装：
composer require symfony/var-dumper
Usage:
用法：
require __DIR__.'/vendor/autoload.php';
// create a variable, which could be anything!
$someVar = ...;
dump($someVar);
