成员变量的PHP大括号语法 [英] PHP curly brace syntax for member variable

问题描述

关于SO的第一个问题，它是真正的RTM候选人.但是我保证你我已经看过了而且似乎找不到.当我发现我错过了一件简单的事情时，我会很高兴地做一个#headpalm.

First question on SO and it's a real RTM candidate. But I promise you I've looked and can't seem to find it. I'll happily do a #headpalm when it turns out to be a simple thing that I missed.

试图弄清楚Zend Framework并遇到以下语法:

Trying to figure out Zend Framework and came across the following syntax:

$this->_session->{'user_id'}

我从未见过用于访问似乎是成员变量的花括号语法.与

I have never seen the curly braces syntax used to access what appears to be a member variable. How is it different than

$this->_session->user_id

我假设_session无关紧要，但由于可能与之无关，因此将其包含在问题中.

I'm assuming that the _session is irrelevant, but including it in the question since it may not be.

花括号是否只是用来包装复合变量名称user_id的清洁约定?还是某种特殊的访问器?

Are the curly braces just a cleanliness convention that attempts to wrap the compound variable name user_id? Or is it some kind of a special accessor?

任何指向TFM以便我可以R向上运行的指针都将由衷地感谢.

Any pointers into TFM so I can R up would be humbly appreciated.

非常感谢.请保持温柔.

Many thanks. Please be gentle.

推荐答案

大括号用于显式指定变量名的结尾.例如:

Curly braces are used to explicitly specify the end of a variable name. For example:

echo "This square is {$square->width}00 centimeters broad."; 

因此，您的案例实际上是两个特殊案例的组合.您可以使用花括号来访问类变量，如下所示:

So, your case is really a combination of two special cases. You're allowed to access class variables using curly braces and like so:

$class->{'variable_name'} // Same as $class->variable_name
$class->{'variable' . '_name'} // Dynamic values are also allowed

在您的情况下，您只是用花括号将它们括起来.

And in your case, you're just surrounding them with the curly brace syntax.

请参见 PHP手册，复杂(卷曲)语法".

See the PHP manual, "complex (curly) syntax."

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