取消字母首行的缩进

Question

这是一个简单的例子：

\documentclass[12pt]{letter}
\setlength{\parindent}{15pt}
\signature{Doorknob}

\begin{document}
\begin{letter}{}
    \noindent \opening{Dear TeX Stack Exchange,}

    Waffles are pancakes with built-in syrup reservoirs.

    Unicorns are magically weaponized ponies.

    This is a generic paragraph.

    \closing{Sincerely,}
\end{letter}
\end{document}

当我尝试查看使用该代码创建的文档时，尽管有该\noindent命令，但开头的一行（“Dear TeX Stack Exchange”）仍然缩进。

我怎样才能告诉 LaTeX 不要缩进信件的开头行？

Answer 1

该类建立在零letter假设之上。\parindent

修补\opening命令：

\documentclass[12pt]{letter}
\usepackage{showframe} % just for the example
\usepackage{etoolbox}

\patchcmd{\opening}{#1}{\noindent#1}{}{}

\setlength{\parindent}{15pt}

\signature{Doorknob}

\begin{document}

\begin{letter}{Some Body\\
  Some Where\\
  42 Some Street}

\opening{Dear TeX Stack Exchange,}

Waffles are pancakes with built-in syrup reservoirs.

Unicorns are magically weaponized ponies.

This is a generic paragraph.

\closing{Sincerely,}

\end{letter}

\end{document}

Answer 2

将该opening行替换为：

\opening{\noindent Dear TeX Stack Exchange,}