为什么 PHP 不支持字符串中 const 的大括号扩展？
PHP 支持这个：
$z = 5;
$str = "z is $z"; // result: "z is 5"
并且它支持这个：
$c = new StdClass();
$c->x = 9;
$str = "x is {$c->x}"; // result: "x is 9"
但它不支持这个：
class abc
{
const n = 2;
}
$str = "x is {abc::n}"; // result: "x is {abc::n}"
为什么 PHP 不 支持通过大括号语法插入常量？看来应该...
PHP supports this:
$z = 5;
$str = "z is $z"; // result: "z is 5"
and it supports this:
$c = new StdClass();
$c->x = 9;
$str = "x is {$c->x}"; // result: "x is 9"
but it does NOT support this:
class abc
{
const n = 2;
}
$str = "x is {abc::n}"; // result: "x is {abc::n}"
Why does PHP not support insertion of consts via the curly-brace syntax? Seems like it should...
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curly 语法是扩展的变量语法。它用于将变量插入字符串中。正如 PHP 中的变量以
$开头一样，其他所有内容都会产生语法错误。但你可以做的是调用变量函数。因此你可以这样做：
但这通常是不合适的。相反，请使用字符串连接：
The curly syntax is the extended variable syntax. It is used to interpolate variables into strings. And as in PHP variables start with
$everything else will yield a syntax error.But what you can do is call variable-functions. Thus you could do:
But that's a hack which normally isn't appropriate. Instead please use string concatenation: