\keys_set_groups:nnn 的严格版本

Question

下面是一段小代码，其中宏允许的键值是一个不需要的功能：例如， single[both = OK, only = KO]没有像我希望的那样给出任何错误。但另一方面，我也想吃掉这种不需要的键：参见\single内部的调用\both。具体来说，我想\single在调用时使用选项\both，但也允许从中使用更多选项\both。

\documentclass{article}

\ExplSyntaxOn

\tl_new:N \l_mbc_both_tl
\tl_new:N \l_mbc_only_tl

\keys_define:nn { strict-mode } {
  both .tl_set:N  = \l_mbc_both_tl,
  both .groups:n  = { single-use },
  only .tl_set:N  = \l_mbc_only_tl,
  only  .groups:n = { both-use },
}


\NewDocumentCommand{\single}{ O{} }{
  \group_begin:
    \keys_set_groups:nnn { strict-mode }
                         { single-use }
                         { #1 }

    Single used...
  \group_end:
}


\NewDocumentCommand{\both}{ O{} }{
  \group_begin:
    \keys_set:nn { strict-mode } { #1 }

    Both used... ~ \single[#1]
  \group_end:
}

\ExplSyntaxOff


\begin{document}

\single[both = OK]

\single[both = OK, only = KO]

\single[after = math KO]

\both[both = OK]

\both[both = OK, only = OK]

\both[after = math OK]

\end{document}

有没有办法定义只允许在一个环境中使用的子键？

Answer 1

一种方法是使用两条路径。然后处理应接受其他密钥的命令，方法是首先针对一条路径处理已知密钥，然后针对另一条路径处理剩余密钥。这样，两个命令都会为完全未知的密钥（after）生成错误，而限制性更强的命令也会为专门为扩展性更强的命令（only）定义的密钥生成错误。

在下面的代码中，我通过排版“未知密钥”消息来防止错误，这只是为了举例。显然，您可以在实际代码中重新定义它，或者直接删除它并使用默认消息。

\documentclass{article}

\ExplSyntaxOn
% 
% internal names should be double-underscored
\tl_new:N \l__mbc_both_tl
\tl_new:N \l__mbc_only_tl

\keys_define:nn { mbc / strict-mode / common } {% try to guarantee unique name space
  both .tl_set:N  = \l__mbc_both_tl,
  unknown .code:n = { % just for testing
    \texttt{\l_keys_key_str}  ~ not ~ recognised!  \par   
  },
}
\keys_define:nn { mbc / strict-mode / exclusive } {% try to guarantee unique name space
  only .tl_set:N  = \l__mbc_only_tl,
}


\NewDocumentCommand {\single}{ O{} }{
  \group_begin:
    \keys_set:nn { mbc / strict-mode / common  } { #1 }
    \texttt{\textbackslash l \_\_ mbc \_ both \_ tl} ~ is ~ \texttt{\l__mbc_both_tl}\par
    \texttt{\textbackslash  l \_\_ mbc \_ only \_ tl} ~ is ~ \texttt{\l__mbc_only_tl}\par
  \group_end:
}


\NewDocumentCommand {\both}{ O{} }{
  \group_begin:
    \keys_set_known:nnN { mbc / strict-mode / exclusive } { #1 } \l_tmpa_tl
    \keys_set:nV { mbc / strict-mode / common } \l_tmpa_tl
    \texttt{\textbackslash l \_\_ mbc \_ both \_ tl} ~ is ~ \texttt{\l__mbc_both_tl}\par
    \texttt{\textbackslash  l \_\_ mbc \_ only \_ tl} ~ is ~ \texttt{\l__mbc_only_tl}\par
  \group_end:
}

\ExplSyntaxOff


\begin{document}

\single[both = OK]

\single[both = OK, only = KO]

\single[after = math KO]

\both[both = OK]

\both[both = OK, only = OK]

\both[after = math OK]

\end{document}