赋予变量默认值的最佳方法(模拟Perl ||，|| =) [英] Best way to give a variable a default value (simulate Perl ||, ||= )

问题描述

我喜欢在Perl中做这种事情:$foo = $bar || $baz如果$bar为空或未定义，则将$baz分配给$foo.您还具有$foo ||= $bletch，如果$foo未定义或为空，则只会将$bletch分配给$foo.

I love doing this sort of thing in Perl: $foo = $bar || $baz to assign $baz to $foo if $bar is empty or undefined. You also have $foo ||= $bletch which will only assign $bletch to $foo if $foo is not defined or empty.

在这种情况下，三元运算符既乏味又累人.当然可以在PHP中使用一种简单，优雅的方法吗?

The ternary operator in this situation is tedious and tiresome. Surely there's a simple, elegant method available in PHP?

还是使用isset()的自定义函数的唯一答案?

Or is the only answer a custom function that uses isset()?

推荐答案

在PHP 7中，我们终于有了一种优雅的方法.它称为空合并运算符.您可以像这样使用它:

In PHP 7 we finally have a way to do this elegantly. It is called the Null coalescing operator. You can use it like this:

$name = $_GET['name'] ?? 'john doe';

这等效于

$name = isset($_GET['name']) ? $_GET['name']:'john doe';

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