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任意常数命令

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任意常数命令

在证明定理时，我有时会定义任意常数，然后引用它们。这些常数并不重要，而且在证明之后也不需要记住。这就是为什么我通常采用一种符号，即每次需要定义新常数时，C_i索引都会增加。i

我想知道我是否可以自动执行此操作。特别是因为当我重新整理校样时，我必须返回并确保索引在我的手稿中是有序的。

我的理想设置是定义两个命令\resetconstants并\const执行如下操作

\resetconstants{D}
This is my first constant \const{name1} and my second constant \const{name2}
but I can also reference my first constant \const{name1}

\resetconstants{E}
New constants are here \const{name1}

\resetconstants{D}
Resetting constants means that previous ones are completely 
forgotten so that \const{name1} is a brand new constant.

输出将是

This is my first constant D_1 and my second constant D_2
but I can also reference my first constant D_1.

New constants are here E_1.

Resetting constants means that previous ones are completely 
forgotten so that D_1 is a new constant.

我该如何实现这个？我知道如何定义计数器，但不知道如何定义键值查找表。有没有一个包可以更容易地实现这个？

答案1

这是一个裸乳胶方法。排版由其\rc@useconst第一个参数是字母，第二个参数是与当前常量关联的数字来控制。如果您想更改常量的显示方式，只需更改此宏的定义即可。

\documentclass{article}
\makeatletter

\newcount\rc@count
\rc@count=1\relax

% initialize list of constants
\let\rc@clearconstantlist\empty

% This command takes the name of a constant and undefines it.
\newcommand\rc@clearconstant[1]{\global\expandafter\let\csname rc@const@#1\endcsname\undefined}

% Iterate over the lists of
\newcommand\resetconstants[1]{%
    \def\rc@constname{#1}% Set the new base name of the constants to the argument
    \global\rc@count=1\relax % Reset the constant counter to 1
    \bgroup 
        \let\\\rc@clearconstant % map over the list of constants that have been defined, clearing each of them.
        \rc@clearconstantlist
        \global\let\rc@clearconstantlist\empty % Globally empty the list of constants.
    \egroup
}
\newcommand\const[1]{%
    \@ifundefined{rc@const@#1}{%
        % Globally store the expansion of the current constant in a macro
        \expandafter\xdef\csname rc@const@#1\endcsname{%
           \noexpand\rc@useconst{\rc@constname}{\the\rc@count}%
        }%
        % Add this macro to the list of things that need to be cleared.
        \g@addto@macro\rc@clearconstantlist{\\{#1}}%
        \global\advance\rc@count1\relax
    }{}%
    % Display the output
    \csname rc@const@#1\endcsname
}

% Redefine this command to change the way that the constants are typeset.
% #1 -- the letter, i.e., D or E
% #2 -- the number of the constant, i.e., 1, 2
\newcommand\rc@useconst[2]{{#1}\textsubscript{#2}}
\makeatother

\begin{document}

\resetconstants{D}
This is my first constant \const{name1} and my second constant \const{name2}
but I can also reference my first constant \const{name1}

\resetconstants{E}
New constants are here \const{name1}

\resetconstants{D}
Resetting constants means that previous ones are completely
forgotten so that \const{name1} is a brand new constant.

\end{document}

我使用的是标准 tex 列表迭代技术，即将列表存储为\mylist具有主体的宏\\{first-entry}\\{second-entry}...\\{last-entry}。因此，空列表只是一个具有空扩展文本的零参数宏。要初始化空列表或清空我已经拥有的列表，我只需说\let\mylist\empty。要向列表添加元素，我使用\g@addto@macro\mylist{\\{new-entry}}。宏\g@addto@macro全局将文本添加到没有参数的宏主体中。

为了迭代此列表，我们将重新定义\\为迭代器，然后扩展。应该在本地\mylist重新定义，因为已经做了其他事情。\\\\

\bgroup % ensure local scope
    \let\\\rc@clearconstant % The function I'm mapping over my list is \rc@clearconstant 
    \rc@clearconstantlist % Map over the list, clearing each constant
    \global\let\rc@clearconstantlist\empty % Globally empty the list of constants.
\egroup % This ends the scope and the value of `\\` is restored.

答案2

\documentclass{article}
\usepackage{xparse}
\ExplSyntaxOn
\int_new:N \g_tohi_const_int
\int_new:N \g_tohi_const_sub_int
\tl_new:N  \g_tohi_const_char_tl

\cs_new_protected:Nn \tohi_print_constant:nn 
{
  #1 \textsubscript {#2} 
} 

\NewDocumentCommand\resetconstants{m}
{
 \int_gincr:N \g_tohi_const_int
 \int_gzero:N \g_tohi_const_sub_int
 \tl_gset:Nn  \g_tohi_const_char_tl {#1}
}

\NewDocumentCommand\const{m}
{
  \tl_if_exist:cTF
   {
    c_tohi_const_\int_use:N\g_tohi_const_int _#1_tl
   }
   {
    \tl_use:c {c_tohi_const_\int_use:N\g_tohi_const_int _#1_tl }
   }
   {
    \int_gincr:N \g_tohi_const_sub_int
    \tl_const:cx {c_tohi_const_\int_use:N\g_tohi_const_int _#1_tl }
     { \exp_not:N\tohi_print_constant:nn {\g_tohi_const_char_tl }{\int_use:N \g_tohi_const_sub_int}}
    \tl_use:c {c_tohi_const_\int_use:N\g_tohi_const_int _#1_tl }
   }
}

\ExplSyntaxOff
\begin{document}

\resetconstants{D}
This is my first constant \const{name1} and my second constant \const{name2}
but I can also reference my first constant \const{name1}

\resetconstants{E}
New constants are here \const{name1}

\resetconstants{D}
Resetting constants means that previous ones are completely
forgotten so that \const{name1} is a brand new constant.
\end{document}

在此处输入图片描述

答案3

\resetconstants您可以使用在发布时清除的属性列表。

\documentclass{article}
\usepackage{xparse}

\ExplSyntaxOn

\NewDocumentCommand{\const}{m}
 {
  \tohiko_constant_use:n { #1 }
 }
\NewDocumentCommand{\resetconstants}{m}
 {
  \tohiko_constant_reset:n { #1 }
 }

\int_new:N \g_tohiko_constant_count_int
\tl_new:N \g_tohiko_constant_name_tl
\prop_new:N \g_tohiko_constant_prop

\cs_new_protected:Nn \tohiko_constant_use:n
 {
  \prop_if_in:NnF \g_tohiko_constant_prop { #1 }
   {
    \int_gincr:N \g_tohiko_constant_count_int
    \prop_gput:Nnx \g_tohiko_constant_prop
     { #1 }
     { \int_to_arabic:n { \g_tohiko_constant_count_int } }
   }
  \ensuremath
   {
    \tl_use:N \g_tohiko_constant_name_tl
    \sb { \prop_item:Nn \g_tohiko_constant_prop { #1 } }
   }
 }
\cs_new_protected:Nn \tohiko_constant_reset:n
 {
  \tl_gset:Nn \g_tohiko_constant_name_tl { #1 }
  \prop_clear:N \g_tohiko_constant_prop
  \int_gzero:N \g_tohiko_constant_count_int
 }

\ExplSyntaxOff

\begin{document}

\resetconstants{D}
This is my first constant \const{name1} and my second constant \const{name2}
but I can also reference my first constant \const{name1}

\resetconstants{E}
New constants are here \const{name1}

\resetconstants{D}
Resetting constants means that previous ones are completely 
forgotten so that \const{name1} is a brand new constant.

\end{document}

在此处输入图片描述

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