ReflectionParameter::getDefaultValue()

(PHP 5 >= 5.0.3, PHP 7)

Gets default parameter value

说明

publicReflectionParameter::getDefaultValue(void) : mixed

Gets the default value of the parameter for a user-defined function or method. If the parameter is not optional aReflectionExceptionwill be thrown.

参数

此函数没有参数。

返回值

The parameters default value.

范例

Getting default values of function parameters

<?php
function foo($test, $bar = 'baz')
{
    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->getDefaultValue() . PHP_EOL;
    }
    echo PHP_EOL;
}
?>

以上例程会输出：

Name: test
Name: bar
Default value: baz

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::isDefaultValueAvailable() 检查是否有默认值。
• ReflectionParameter::getDefaultValueConstantName() Returns the default value's constant name if default value is constant or null
• ReflectionParameter::isPassedByReference() Checks if passed by reference

[Editor's note: fixed on user's request]
Getting `Uncaught ReflectionException: Internal error: Failed to retrieve the default value`?
You have to wrap this inside ->isDefaultValueAvailable().