php - 使用 heredoc 语法访问字符串中的静态变量的正确方法？

Question

假设我在我的类中有一个名为 $_staticVar 的静态变量，我正试图像这样访问它。该变量有一个成员 aString，它的字符串值为 "my static variable"

    echo <<<eos

    <br/>This is the content of my static variable, 
    self::$_staticVar->$aString
    which is not getting accessed properly in heredoc syntax. <br/>

eos;

输出:

Notice: Undefined variable: _staticVar in /path/to/file.php on line some_line_number

<br/>This is the content of my static variable,
self::->my static variable,
which is not getting accessed properly in heredoc syntax.<br/>

PHP^docs对于 heredoc对此什么也没说。

---

我试过这个:

    echo <<<eos

    <br/>This is the content of my static variable,<br/>
    {${self::$_staticVar->$aString}}<br/>
    which is not getting accessed properly in heredoc syntax. <br/>

eos;

它不起作用。
输出:

Notice: Undefined variable: _staticVar in /path/to/file.php on line some_line_number

<br/>This is the content of my static variable,
   
which is not getting accessed properly in heredoc syntax.<br/>

---

这是我的 PHP 设置:

display_startup_errors = on
display_errors = On
error_reporting = E_ALL | E_STRICT

Answer 1

我相当确定您必须使用本地或导入变量进行字符串插值。最简单的解决方案？为什么，当然是本地化:

    $_staticVar = self::$_staticVar; // or did you mean self::_staticVar? Not too clear on that.

    echo <<<eos

    <br/>Something {$_staticVar->something} more of something <br/>

eos;

---

至于您的示例不起作用的原因:

    echo <<<eos

    <br/>Something self::$_staticVar->{$something} more of something <br/>

eos;

插入 undefined variable $something 和 $_staticVar，这会导致空字符串和通知。

    echo <<<eos

    <br/>Something {${self::$$_staticVar->{$something}}} more of something <br/>

eos;

插入一些绝对不存在且永远不会存在的值，这真的很令人困惑，但你知道它不起作用。