expandable optional parameter to enumerate environment

Question

The MWE below, by using paralist package, is supposed to allow \begin{enumerate}[...] where ... is flexible in "some way" (inherits from enumerates above).

\documentclass[a4paper,10pt]{report}

\usepackage{paralist,xargs}

\newcommand\mwe[2]{[{\ref{#1}.}.#2]}

\begin{document}

\newenvironmentx{enumwe}[2][2=1]{%
  \begin{enumerate}\mwe{#1}{#2}%
  %\expandafter\begin\expandafter{\expandafter enumerate\expandafter}\mwe{#1}{#2}%
  \ignorespaces%
}{\end{enumerate}%
  \ignorespacesafterend%
}

\begin{enumerate}[{A}1]

\item \label{one} {\bfseries~Appendix One}

  \begin{enumwe}{one}
    \item text
  \end{enumwe}

\end{enumerate}

\end{document}

However, the commented line seems a wrong attempt, while the MWE typesets wrong.

The expanded result expected would be the following.

\begin{enumerate}[{A}1]
\item \label{one} {\bfseries~Appendix One}
  \begin{enumerate}[{A1.}1.]
    \item text
  \end{enumerate}
\end{enumerate}

I appreciate any help or suggestions.

P.S.: I actually need to expand a macro in the optional parameter to enumerate environment, like \begin{enumerate}[\mwe{...}1.], but it's not working (the ?? occurs everywhere) and this MWE is my approach, but I got stuck with the weird error:

! LaTeX Error: \begin{enumerate} on input line 21 ended by \end{enumerate}.

Answer 1

\expandafter only steps over a single token not brace groups, so the simplest thing is to put everything you want to step over into a single token:

\documentclass[a4paper,10pt]{report}

\usepackage{paralist,xargs}

\newcommand\mwe[2]{[{\ref{#1}.}.#2]}

\begin{document}

\newenvironmentx{enumwe}[2][2=1]{%
  \def\temp{\begin{enumerate}}%
  \expandafter\temp\mwe{#1}{#2}%
  \ignorespaces%
}{\end{enumerate}%
  \ignorespacesafterend%
}

\begin{enumerate}[{A}1]

\item \label{one} {\bfseries~Appendix One}

  \begin{enumwe}{one}
    \item text
  \end{enumwe}

\end{enumerate}

\end{document}