在lua中构建Latex/Tex参数 [英] Building Latex/Tex arguments in lua

问题描述

我用lua做一些复杂的工作来为Tex/LaTex中的宏准备参数.

I use lua to make some complex job to prepare arguments for macros in Tex/LaTex.

第一部分 这是一个愚蠢的最小示例:

Part I Here is a stupid minimal example :

\newcommand{\test}{\luaexec{tex.print("11,12")}}% aim to create 11,12
\def\compare#1,#2.{\ifthenelse{#1<#2}{less}{more}}
\string\compare11,12. : \compare11,12.\\ %answer is less
\string\test : \test\\ % answer is 11,12
\string\compare : \compare\test. % generate an error

最后一行创建一个错误.显然，Tex没有检测到\ test中包含的，".

The last line creates an error. Obviously, Tex did not detect the "," included in \test.

如何将\ test理解为11，后跟，再跟12，而不是字符串11,12，最后用作\ compare的正确格式参数?

How can I do so that \test is understood as 11 followed by , followed by 12 and not the string 11,12 and finally used as a correctly formed argument for \compare ?

推荐答案

TeX的工作方式存在一些误解.

There are several misunderstandings of how TeX works.

您的\compare宏要查找的内容后面是逗号，然后是句点.但是，当您致电

Your \compare macro wants to find something followed by a comma, then something followed by a period. However when you call

\compare\test

没有找到

逗号，因此TeX一直在寻找它，直到找到文件的结尾或\par(或者也有一个空行).请注意，TeX 从不在查找宏参数时会扩展宏.

no comma is found, so TeX keeps looking for it until finding either the end of file or a \par (or a blank line as well). Note that TeX never expands macros when looking for the arguments to a macro.

你可能会做

\expandafter\compare\test.

假设\test立即以所需的格式扩展为令牌，但不会扩展，因为\test的扩展为

provided that \test immediately expands to tokens in the required format, which however don't, because the expansion of \test is

\luaexec{tex.print("11,12")}

，并且用大括号隐藏了逗号，因此不算在内.但这仍然无济于事.

and the comma is hidden by the braces, so it doesn't count. But it wouldn't help nonetheless.

问题是一样的:当您这样做

The problem is the same: when you do

\newcommand{\test}{\luaexec{tex.print("11,12")}}

该参数未扩展 .您可能在\edef中使用了扩展定义"，但是问题是\luaexec不能完全扩展.

the argument is not expanded. You might use "expanded definition" with \edef, but the problem is that \luaexec is not fully expandable.

如果愿意

\edef\test{\directlua{tex.sprint("11,12")}}

然后

\expandafter\compare\test.

会工作的.

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