php php中的动态类属性$$value
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dynamic class property $$value in php
提问by Cameron A. Ellis
How can i reference a class property knowing only a string?
如何引用仅知道字符串的类属性？
class Foo
{
public $bar;
public function TestFoobar()
{
$this->foobar('bar');
}
public function foobar($string)
{
echo $this->$$string; //doesn't work
}
}
what is the correct way to eval the string?
评估字符串的正确方法是什么？
回答by Antonio Haley
You only need to use one $ when referencing an object's member variable using a string variable.
使用字符串变量引用对象的成员变量时，只需使用一个 $。
echo $this->$string;
回答by Rick
If you want to use a property value for obtaining the name of a property, you need to use "{" brackets:
如果要使用属性值来获取属性的名称，则需要使用“{”括号：
$this->{$this->myvar} = $value;
Even if they're objects, they work:
即使它们是对象，它们也能工作：
$this->{$this->myobjname}->somemethod();
回答by Matthew H.
As the others have mentioned, $this->$string should do the trick.
正如其他人所提到的， $this->$string 应该可以解决问题。
However, this
然而，这
$this->$$string;
will actually evaluate string, and evaluate again the result of that.
将实际评估字符串，并再次评估其结果。
$foo = 'bar';
$bar = 'foobar';
echo $$foo; //-> $'bar' -> 'foobar'
回答by Mike Stanford
you were very close. you just added 1 extra $ sign.
你非常接近。您刚刚添加了 1 个额外的 $ 符号。
public function foobar($string)
{
echo $this->$string; //will work
}
回答by Marc W
echo $this->$string; //should work
You only need $$stringwhen accessing a local variable having only its name stored in a string. Since normally in a class you access it like $obj->property, you only need to add one $.
仅$$string在访问仅将其名称存储在字符串中的局部变量时才需要。因为通常在一个类中您可以像访问它一样$obj->property，所以您只需要添加一个$.
回答by Marc W
To remember the exact syntax, take in mind that you use a $more than you normally use. As you use $object->propertyto access an object property, then the dynamic access is done with $object->$property_name.
要记住确切的语法，请记住您使用的 a$比通常使用的多。当您$object->property用来访问对象属性时，动态访问是通过$object->$property_name.
