ReflectionParameter::getDefaultValueConstantName()

(PHP 5 >= 5.4.6, PHP 7)

Returns the default value's constant name if default value is constant or null

说明

publicReflectionParameter::getDefaultValueConstantName(void) : string

Returns the default value's constant name of the parameter of a user-defined function or method, if default value is constant or null. If the parameter is not optional aReflectionExceptionwill be thrown.

参数

此函数没有参数。

返回值

Returns string on success orNULLon failure.

范例

Getting default values' constant names of function parameters

<?php
function foo($test, $bar = PHP_INT_MIN)
{
    echo $test . $bar;
}
$function = new ReflectionFunction('foo');
foreach ($function->getParameters() as $param) {
    echo 'Name: ' . $param->getName() . PHP_EOL;
    if ($param->isOptional()) {
        echo 'Default value: ' . $param->getDefaultValueConstantName() . PHP_EOL;
    }
    echo PHP_EOL;
}
?>

以上例程会输出：

Name: test
Name: bar
Default value: PHP_INT_MIN

注释

Note:

Due to implementation details, it is not possible to get the default value of built-in functions or methods of built-in classes. Trying to do this will result aReflectionExceptionbeing thrown.

参见

• ReflectionParameter::isOptional() Checks if optional
• ReflectionParameter::isDefaultValueConstant() Returns whether the default value of this parameter is a constant
• ReflectionParameter::getDefaultValue() Gets default parameter value