Suppressing indentation of the next paragraph

Question

I'm trying to define an environment/command, with the following property: The immediate paragraph after the environment must not be indented. The following shows my attempt at defining such environment/command:

\makeatletter    
\newenvironment{NoIndEnv}{}{\par\@afterindentfalse\@afterheading}    
\newcommand{\NoIndCmd}[1]{#1 \par\@afterindentfalse\@afterheading}    
\makeatother

Now compare the following two:

\begin{NoIndEnv}
   Text ...
\end{NoIndEnv}

Some text ...

and

\NoIndCmd{Text ...}

Some text ...

For some reason, the environment definition works only if it is placed after a \section command; i.e.:

\section{}

\begin{NoIndEnv}
   Text ...
\end{NoIndEnv}

Some text ...

Could you please help me figure out what's wrong?

Answer 1

The problem is that \@afterindentfalse\@afterheading are done inside a group, in the environment case. Solution: do them after the group has ended.

\newenvironment{NoIndEnv}
  {}
  {\par\aftergroup\@afterindentfalse\aftergroup\@afterheading}