[英]How to create static class constant variable from another constant variable?
I have a constant called PREFIX defined in constants.php. 我在constants.php中定义了一个名为PREFIX的常量。 In class Foo, I would like to create a static class constant with PREFIX as the prefix. 在类Foo中,我想创建一个以PREFIX作为前缀的静态类常量。 But I get a syntax error on that const definition line. 但是我在const定义行上遇到语法错误。
require_once 'constants.php';
class Foo {
const FOO_CONST = PREFIX . 'bar';
public function __construct() {
}
}
In PHP a const
must be a value, not an expression. 在PHP中, const
必须是值,而不是表达式。 So const FOO_CONST = 'foo' . 'bar';
所以const FOO_CONST = 'foo' . 'bar';
const FOO_CONST = 'foo' . 'bar';
won't work either. 也不行。
You have to use define
or a class member that gets initialized in the constructor instead of a const
. 您必须使用在构造函数而不是const
初始化的define
或类成员。 Initializing a class member outside a class method with an expression does not work either. 使用表达式在类方法外部初始化类成员也不起作用。
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