PHP模板中的未定义变量

Question

I use PHP as a template language in my view layer, Is it possible to make following a little cleaner and more concise?

//in temp.phtlm
<?= (isset($user['name'])) ? $user['name'] : null; ?> 

Unfortunately we can not even define a function for that:

// as you know yet a notice is generated when calling function with undefined parameter
function out($var)
{
        return (isset($var)) ? htmlentities($var) : null;
}

Answer 1

There is no short hand method to do that quicker, no. Any other method would throw an error if $var did not exist at that point.

Depending on your structure/templating system you could use a class to store your var's and use the magic methods __get, __set, __isset, __unset to call your variables. Those methods could then just return null if the var didnt exist. This would require quite a change in your code though. You can find the manual about magic methods here: http://php.net/manual/en/language.oop5.magic.php

As for your original code, i would write it like this:

<?php echo ( isset($var) ? $var : null ); ?> 

Answer 2

//in temp.phtlm
<?=$var?>

//in whatever_your_script_name.php
$template->var = isset($var) ? htmlentities(whatever(convert(encode($var)))) : '';
$template->render('temp.phtml');

Answer 3

使用@运算符是最简单的选择。

<?= @$user['name']; ?>