org/apache/tomcat/util/net/AbstractEndpoint.java

等小写字母或字符串表示，称为常元(constants) 个体变元(variables):不确定的个体常用字母

WordPress 在 wp-includes/default-constants 定义了 WordPress 常用常量的默认值，这些常量都可以在 wp-config.php 中预先定义，这里都会判断如果在 wp-config.php 定义了，就不设置默认值。...

Flag if-then-else chains that check against constants (only).

Unnamed constants embedded in expressions are easily overlooked and often hard to understand: