在一个类中，我在第22行得到了一个"Unexpected"'[…]"，我一辈子都不知道为什么。
错误在的第22行
<?php
namespace oowp'post;
global $wpdb;
class PostObjectQueryBuilder extends QueryBuilder implements IExtendable {
use Extendable;
// WP Tables
private $tablePosts; //The table of Posts.
private $tablePostmeta; //The Meta Content (a.k.a. Custom Fields) table.
private $tableComments; //The Comments table.
private $tableCommentmeta; //The table contains additional comment information.
private $tableTerms; //The terms table contains the 'description' of Categories, Link Categories, Tags.
private $tableTermTaxonomy; //The term_taxonomy table describes the various taxonomies (classes of terms). Categories, Link Categories, and Tags are taxonomies.
private $tableTermRelationships; //The term relationships table contains link between the term and the object that uses that term, meaning this file point to each Category used for each Post.
private $tableUsers; //The table of Users.
private $tableUsermeta; //The usermeta table contains additional user information, such as nicknames, descriptions and permissions.
private $tableLinks; //The table of Links.
private $tableOptions; //The Options table.
// LINE 22 BELOW
const BASE_QUERY = "SELECT wp.ID FROM `{$this->tablePosts}` wp
INNER JOIN `{$this->tablePostMeta}` wm ON (wm.`post_id` = wp.`ID`)
INNER JOIN `{$this->tableTermRelationships}` wtr ON (wp.`ID` = wtr.`object_id`)
INNER JOIN `{$this->tableTermTaxonomy}` wtt ON (wtr.`term_taxonomy_id` = wtt.`term_taxonomy_id`)
INNER JOIN `{$this->tableTerms}` wt ON (wt.`term_id` = wtt.`term_id`)";
我尝试过重写有问题的行，并尝试将const声明移到顶部，同时删除use语句。两者都不起作用。
这是因为类常量需要有一个常数值，而您的定义不是常量。
来自类常量手册：
该值必须是常量表达式，而不是（例如）变量，属性或函数调用。
您可以通过移除const并将BASE_QUERY转换为$BASE_QUERY并移除$this->作为其他变量来证明您的语法在类外是正确的，它应该会成功解析。
您可以将此表达式定义为成员变量，但不能在初始化期间定义。这是因为PHP中的成员变量也必须初始化为常量表达式。最简单的解决方案是在类中定义$BASE_QUERY，然后在构造函数中初始化它。
我不明白为什么要创建一个常量来获得基本查询。
表达式不允许作为类常数值
有一个返回基本查询的函数很简单，你可以在任何你想使用它的地方调用它
public function getBaseQuery()
{
return "SELECT wp.ID FROM `{$this->tablePosts}` wp
INNER JOIN `{$this->tablePostMeta}` wm ON (wm.`post_id` = wp.`ID`)
INNER JOIN `{$this->tableTermRelationships}` wtr ON (wp.`ID` = wtr.`object_id`)
INNER JOIN `{$this->tableTermTaxonomy}` wtt ON (wtr.`term_taxonomy_id` = wtt.`term_taxonomy_id`)
INNER JOIN `{$this->tableTerms}` wt ON (wt.`term_id` = wtt.`term_id`)";
}