Is there a way for a command to have a scope within item?

Question

I defined a command

\newcommand{\done}{\color[RGB]{124, 124, 255}}

Is there a way to use it as

\item \done la-la

instead of

\item {\done la-la}

It bothers me to put brackets all the time.
So basically I want \done to have a scope only within \item.

Answer 1

Reset the color with \item

\documentclass{article}
\usepackage{xcolor}
\newcommand\done{\color[RGB]{124, 124, 255}}
\let\Item\item
\renewcommand\item{\normalcolor\Item}

\begin{document}

\begin{enumerate}
\item \done la-la
\item foo
\item \done la-la
\end{enumerate}

\end{document}

Answer 2

Bulding on Gonzalo's solution, you can alter the definition of \item within the Lenumerate environment and behavior outside it will be as normal.

\documentclass{article}

\newenvironment{Lenumerate}{%
  \begingroup
  \let\latexsaveditem\item
  \renewcommand{\item}{\endgroup\begingroup\latexsaveditem}
  \enumerate\begingroup%
}{%
  \endgroup\endenumerate\endgroup%
}

\begin{document}

\begin{Lenumerate}
  \item \bfseries a
  \item \itshape b
  \item \scshape c
  \item d
\end{Lenumerate}

\end{document}

Answer 3

This answer is to be considered somehow experimental; I defined three commands: \Mfitem (to be used exclusively in the first item of the list), \Mitem (to be used exclusively for items different from the first and the last one) and \Mlitem (to be used exclusively for the last item of the list). \Mfitem simply invokes \item and begins a group (without closing it); \Mitem ends a group, opens another one, and then invokes \item (thanks to Caramdir for suggesting this order), and \Mlitem closes the last group before invoking \item. An example:

\documentclass{article}

\newcommand\Mfitem{\begingroup\item}
\newcommand\Mitem{\endgroup\begingroup\item}
\newcommand\Mlitem{\endgroup\item}

\begin{document}

\begin{enumerate}
  \Mfitem \bfseries a
  \Mitem \itshape b
  \Mitem \scshape c
  \Mlitem d
\end{enumerate}

\end{document}

EDIT: Following a suggestion by Caramdir, here's another option: to define a new environment using environment but adding \begingroup at the beginning and \endgroup at the end; now the commands \Mfitem and \Mlitem are no longer necessary:

\documentclass{article}

\newenvironment{Lenumerate}
  {\enumerate\begingroup}
  {\endgroup\endenumerate}

\newcommand\Mitem{\endgroup\begingroup\item}

\begin{document}

\begin{Lenumerate}
  \Mitem \bfseries a
  \Mitem \itshape b
  \Mitem \scshape c
  \Mitem d
\end{Lenumerate}

\end{document}