將成員新增至 \foreach 內的資料庫時出現虛假空格

Question

MWE 增加與迭代最大值成比例的空白\foreach：

這是為什麼？

筆記：

• 這個問題似乎與我之前遇到的問題類似在不應該輸出的情況下輸出文本，但我不知道如何解決這個問題。
• 我猜這是某種與擴展相關的問題，因為\dtlexpandnewvalue需要從資料庫中獲得正確的輸出。

代碼：

\documentclass{article}

\usepackage{pgffor}
\usepackage{datatool}
\usepackage{showframe}

\newcommand*{\InitalizeDB}[1]{% 
    \DTLifdbexists{#1}%
        {\DTLcleardb{#1}}% DB exists, so just clear it
        {\DTLnewdb{#1}}%   DB does not exist, so create it
}%
\newcommand*{\AddMemberToDB}[3]{%
    % #1 = name of DB
    % #2 = db key to be used
    % #3 = member to be added to DB
    \dtlexpandnewvalue%
    \DTLnewrow{#1}%
    \DTLnewdbentry{#1}{#2}{#3}%
}%



\begin{document}
\InitalizeDB{MyDB}
\noindent
abc%
\foreach \x in {2,...,7} {%
    \AddMemberToDB{MyDB}{MyDBKey}{\x}%
}%
def

\bigskip\noindent
Database:\par
\DTLdisplaydb{MyDB}
\end{document}

Answer 1

該巨集透過 an\@dtl@updatekeys定義，並且不會插入到行尾，從而導致不必要的跳過：\@defl@dogetprops\edef%

\newcommand*{\@dtl@updatekeys}[3]{%
  \@sDTLifhaskey{#1}{#2}%
  {%
    \expandafter\dtlcolumnnum\expandafter
      =\dtlcolumnindex{#1}{#2}\relax
    \edef\@dtl@dogetprops{\noexpand\@dtl@getprops
      {\noexpand\@dtl@key}{\noexpand\@dtl@type}%
      {\noexpand\@dtl@colhead}{\noexpand\@dtl@before}%
      {\noexpand\@dtl@after}{\the\csname dtlkeys@#1\endcsname}%
      {\number\dtlcolumnnum}}% <--------- inserted '%'
    \@dtl@dogetprops
    %...
}

由於\@dtl@updatekeys相當大，因此\unskip在添加成員（ 的一部分\AddMemberToDB或內部\foreach）後發出可以解決問題。

\documentclass{article}

\usepackage{pgffor}% http://ctan.org/pkg/pgf
\usepackage{datatool}% http://ctan.org/pkg/datatool
\usepackage{showframe}% http://ctan.org/pkg/showframe

\newcommand*{\InitalizeDB}[1]{% 
    \DTLifdbexists{#1}%
        {\DTLcleardb{#1}}% DB exists, so just clear it
        {\DTLnewdb{#1}}%   DB does not exist, so create it
}%
\newcommand*{\AddMemberToDB}[3]{%
    % #1 = name of DB
    % #2 = db key to be used
    % #3 = member to be added to DB
    \dtlexpandnewvalue%
    \DTLnewrow{#1}%
    \DTLnewdbentry{#1}{#2}{#3}%
}%

\begin{document}
\InitalizeDB{MyDB}
\noindent
abc%
\foreach \x in {2,...,7} {%
    \AddMemberToDB{MyDB}{MyDBKey}{\x}\unskip%
}%
def

\bigskip\noindent
Database:\par
\DTLdisplaydb{MyDB}
\end{document}