Change \parskip only inside enumerate & itemize environment

Question

Is there any way that I can change \\parskip to a different value inside certain environments, namely enumerate and itemize.

I wan

Answer 1

Yes you can; but you will have to alter either the enumerate and itemize environments from your class file (by copying them and adding your \parskip), or by redefining \@listi, which works for all lists:

\makeatletter

\def\@listi{%
  % default settings for base LaTeX classes at 10pt:
  \parsep 4pt plus 2pt minus 1pt
  \topsep 8pt plus 2pt minus 4pt
  \itemsep 4pt plus 2pt minus 1pt
  % your settings:
  \parskip 1em plus 1pt minus 1pt
}

\makeatother

If you want different settings at nested list levels, change \@listii, \@listiii etc.

Answer 2

you can also use:

begin{itemize} \itemsep -5pt
\item foo
\item bar
\end{itemize}

and that will only affect the current list.

Answer 3

If you use the enumitem package, you can say in your preamble

\setlist[itemize]{parsep=0pt}
\setlist[enumerate]{parsep=0pt}

to get what you want. enumitem allows for doing much more list customization, see its documentation for details.

Answer 4

The following addition to the preamble updates enumerate to make the suggested change:

\let\oldenumerate\enumerate% Keep a copy of \enumerate (or \begin{enumerate})
\let\endoldenumerate\endenumerate% Keep a copy of \endenumerate (or \end{enumerate})
\renewenvironment{enumerate}
  {\begin{oldenumerate}
     \setlength{\parskip}{0pt}}% Adjust \parskip to suit your needs
  {\end{oldenumerate}}

Here is a complete minimal example showing the adjustment when setting \parskip to 0pt:

\documentclass{article}
\begin{document}

\begin{enumerate}
  \item First line

    Second line
\end{enumerate}

\let\oldenumerate\enumerate
\let\endoldenumerate\endenumerate
\renewenvironment{enumerate}
  {\begin{oldenumerate}
     \setlength{\parskip}{0pt}}
  {\end{oldenumerate}}

\begin{enumerate}
  \item First line

    Second line
\end{enumerate}

\end{document}

One would do exactly the same for itemize.