类方法中的 PHP Time() 函数

Question

我有一个类Convert 有一个函数date：

<?php
    class Convert{
        public static function datum($timestamp = time()){
            //When $timestamp isn't set use php function time()

           return(date("N" , $timestamp));
        }
    }
?>

//run method
Convert::datum();

这不起作用我收到一个错误： Parse error: syntax error, unexpected '(', expecting ')' in .... on line 3 (function line) ;
函数时间好像没有重新计算。

Answer 1

改变

class Convert{
    public static function datum($timestamp = time()){ // <-- no functions allowed in here
        //When $timestamp isn't set use php function time()

       return(date("N" , $timestamp));
    }
}

进入

class Convert{
    public static function datum($timestamp = NULL){

        //When $timestamp isn't set use php function time()
        $timestamp = ($timestamp !== NULL ? $timestamp : time());

        return(date("N" , $timestamp));
    }
}

在声明函数时，参数只能接受空数据类型或数据。该参数不能设置为接受函数的返回，也不能是动态的。

好

public static function datum($timestamp = NULL){
public static function datum($timestamp = 13524564){
public static function datum($timestamp = '423432'){
public static function datum($timestamp = array()){
public static function datum($timestamp = FALSE){
public static function datum($timestamp = TRUE){

不好

public static function datum($timestamp = time()){
public static function datum($timestamp = (8*2)){
public static function datum($timestamp = $this->someValFromThisClass){
public static function datum($timestamp = 123, $new = $timestamp){