How to use named variables with one environment

Question

Just after there is one code which has been proposed to me in this site.

Instead of using \begin{MyFrame}[1.5cm][2pt][1.3cm][blue][2][8ex], I would like to use something more friendly like \begin{MyFrame}[lenght = 1.5cm , thickness = 2pt , distH = 1.3cm , color = blue, factor = 2 , distV = 8ex].

If it is possible, how can I do that ?

% Source : http://tex.stackexchange.com/questions/33078/frame-with-only-crosses-in-two-opposite-corners/33087#33087

\documentclass{article}
    \usepackage{xparse}
    \usepackage{xcolor}

% Meaning of the variables
%    #1 --> Length : this controls the length of the rules used (default = 1cm)
%    #2 --> Thickness of the rule (default = 0.4pt)
%    #3 --> Horizontal distance between the rules and the text (default = 0.8cm)
%    #4 --> Color of the rule using the xcolor package (default = black)
%    #5 --> Factor is a number controlling the point of intersection of each pair
%           of rules used for the cross (default = 3)
%    #6 --> Vertical distance between the rules and the text (default = 2ex)
    \DeclareDocumentEnvironment{MyFrame}{O{1cm}O{0.4pt}O{0.8cm}O{black}O{3}O{2ex}}
    {%
        \par\hfill\rlap{%
            \bgroup\color{#4}%
            \hskip-\dimexpr#1-#3\relax\rule{#1}{#2}%
            \hskip-\dimexpr#1/#5\relax\rule[-\dimexpr#1-\dimexpr#1/#5\relax]{#2}{#1}%
            \egroup
        }%
        \vskip-\dimexpr#1/#5+\dimexpr#1/#5-#6\relax%
    }
    {%
        \par\nobreak\offinterlineskip\vskip-\dimexpr#1/#5+\dimexpr#1/#5-#6\relax\noindent%
        \hskip-#3\bgroup\color{#4}%
        \rule{#1}{#2}\hskip-\dimexpr#1-\dimexpr#1/#5-#2\relax%
        \rule[-\dimexpr#1/#5-#2\relax]{#2}{#1}\egroup\par
    }

% Just to generate text for the example.
    \usepackage{lipsum}


\begin{document}

\begin{MyFrame}[1.5cm][2pt][1.3cm][blue][6][8ex]
    \lipsum[1]
\end{MyFrame}

\end{document}

Answer 1

A complete translation using keyval

\documentclass{article}
\usepackage{keyval}
\usepackage{xcolor}

\makeatletter
\define@key{myframe}{length}{\def\mf@length{#1}}
\define@key{myframe}{thickness}{\def\mf@thickness{#1}}
\define@key{myframe}{Hdist}{\def\mf@Hdist{#1}}
\define@key{myframe}{Vdist}{\def\mf@Vdist{#1}}
\define@key{myframe}{color}{\def\mf@color{#1}}
\define@key{myframe}{factor}{\def\mf@factor{#1}}
%% set defaults (not Vdist, which depends on current conditions)
\setkeys{myframe}{length=1cm,thickness=0.4pt,Hdist=.8cm,factor=3,color=black}

\newenvironment{MyFrame}[1][]
  {\setkeys{myframe}{Vdist=2ex,#1}%
   \par\hfill\rlap{%
     \bgroup\color{\mf@color}%
     \hskip-\dimexpr\mf@length-\mf@Hdist\relax
     \rule{\mf@length}{\mf@thickness}%
     \hskip-\dimexpr\mf@length/\mf@factor\relax
     \rule[-\dimexpr\mf@length-\dimexpr\mf@length/\mf@factor\relax]{\mf@thickness}{\mf@length}%
     \egroup
   }%
   \vskip-\dimexpr\mf@length/\mf@factor+\dimexpr\mf@length/\mf@factor-\mf@Vdist\relax
   }
   {%
    \par\nobreak\offinterlineskip
    \vskip-\dimexpr\mf@length/\mf@factor+\dimexpr\mf@length/\mf@factor-\mf@Vdist\relax
    \noindent
    \hskip-\mf@Hdist\bgroup\color{\mf@color}%
    \rule{\mf@length}{\mf@thickness}\hskip-\dimexpr\mf@length-
                                    \dimexpr\mf@length/\mf@factor-\mf@thickness\relax
    \rule[-\dimexpr\mf@length/\mf@factor-\mf@thickness\relax]{\mf@thickness}{\mf@length}
    \egroup\par
    }
\makeatother

% Just to generate text for the example.
    \usepackage{lipsum}


\begin{document}

\begin{MyFrame}[length=1.5cm,thickness=2pt,Hdist=1.3cm,color=blue,factor=6,Vdist=8ex]
    \lipsum[1]
\end{MyFrame}

\end{document}

Here is a document example:

\documentclass{article}
\usepackage{keyval}
\usepackage{xcolor}
\usepackage[margin=2cm]{geometry}
\pagestyle{empty}
\makeatletter
\define@key{myframe}{length}{\def\mf@length{#1}}
\define@key{myframe}{thickness}{\def\mf@thickness{#1}}
\define@key{myframe}{Hdist}{\def\mf@Hdist{#1}}
\define@key{myframe}{Vdist}{\def\mf@Vdist{#1}}
\define@key{myframe}{color}{\def\mf@color{#1}}
\define@key{myframe}{factor}{\def\mf@factor{#1}}
%% set defaults (not Vdist, which depends on current conditions)
\setkeys{myframe}{length=1cm,thickness=0.4pt,Hdist=.8cm,factor=3,color=black}

\newenvironment{MyFrame}[1][]
  {\setkeys{myframe}{Vdist=2ex,#1}%
   \par\hfill\rlap{%
     \bgroup\color{\mf@color}%
     \hskip-\dimexpr\mf@length-\mf@Hdist\relax
     \rule{\mf@length}{\mf@thickness}%
     \hskip-\dimexpr\mf@length/\mf@factor\relax
     \rule[-\dimexpr\mf@length-\dimexpr\mf@length/\mf@factor\relax]{\mf@thickness}{\mf@length}%
     \egroup
   }%
   \vskip-\dimexpr\mf@length/\mf@factor+\dimexpr\mf@length/\mf@factor-\mf@Vdist\relax
   }
   {%
    \par\nobreak\offinterlineskip
    \vskip-\dimexpr\mf@length/\mf@factor+\dimexpr\mf@length/\mf@factor-\mf@Vdist\relax
    \noindent
    \hskip-\mf@Hdist\bgroup\color{\mf@color}%
    \rule{\mf@length}{\mf@thickness}\hskip-\dimexpr\mf@length-
                                    \dimexpr\mf@length/\mf@factor-\mf@thickness\relax
    \rule[-\dimexpr\mf@length/\mf@factor-\mf@thickness\relax]{\mf@thickness}{\mf@length}
    \egroup\par
    }
\makeatother

% Just to generate text for the example.
    \usepackage{lipsum}


\begin{document}
\small

\begin{MyFrame}[length=1.5cm,thickness=2pt,Hdist=1.3cm,color=blue,factor=4,Vdist=8ex]
    \lipsum[2]
\end{MyFrame}

\begin{MyFrame}
\lipsum[2]
\end{MyFrame}

\begin{MyFrame}[length=3cm,thickness=4pt,Hdist=1.5cm,color=red!60]
\lipsum[2]
\end{MyFrame}

\begin{MyFrame}[length=1.5cm,thickness=2pt,Hdist=1.3cm,color=blue,factor=2,Vdist=8ex]
\lipsum[2]
\end{MyFrame}

\begin{MyFrame}[length=1cm,thickness=7pt,Hdist=0.6cm,color=olive!60,factor=4,Vdist=0ex]
\lipsum[2]
\end{MyFrame}

\end{document}

Answer 2

Another solution based on pgfkeys (slightly more verbose).

\documentclass{article}
\usepackage{xcolor}
\usepackage{pgfkeys}

\pgfkeys{%
  /MyFrame/.is family,
  /MyFrame/length/.initial = {1cm},
  /MyFrame/thickness/.initial = {0.4pt},
  /MyFrame/Hdist/.initial = {0.8cm},
  /MyFrame/color/.initial = {black},
  /MyFrame/factor/.initial = {3},
  /MyFrame/Vdist/.initial = {2ex}}  

% To make sure the environment is definable
\newenvironment{MyFrame}{}{}

\makeatletter
\def\MyFrame{%
  \@ifnextchar[{\MyFrame@i}{\MyFrame@i[]}}%]
\def\MyFrame@i[#1]{%
  \bgroup
  \pgfkeys{MyFrame/.cd,Vdist=2ex,#1}%
  \par\hfill\rlap{%
    \bgroup\color{\pgfkeysvalueof{/MyFrame/color}}%
    \hskip-\dimexpr\pgfkeysvalueof{/MyFrame/length} - 
      \pgfkeysvalueof{/MyFrame/Hdist}\relax
    \rule{\pgfkeysvalueof{/MyFrame/length}}{%
      \pgfkeysvalueof{/MyFrame/thickness}}%
    \hskip-\dimexpr\pgfkeysvalueof{/MyFrame/length} / 
      \pgfkeysvalueof{/MyFrame/factor}\relax
    \rule[-\dimexpr\pgfkeysvalueof{/MyFrame/length} - 
      \dimexpr\pgfkeysvalueof{/MyFrame/length} / 
      \pgfkeysvalueof{/MyFrame/factor}\relax]{%
        \pgfkeysvalueof{/MyFrame/thickness}}{%
        \pgfkeysvalueof{/MyFrame/length}}%
    \egroup
  }%
  \vskip-\dimexpr\pgfkeysvalueof{/MyFrame/length} / 
    \pgfkeysvalueof{/MyFrame/factor} + 
    \dimexpr\pgfkeysvalueof{/MyFrame/length} / 
    \pgfkeysvalueof{/MyFrame/factor} - 
    \pgfkeysvalueof{/MyFrame/Vdist}\relax}

\def\endMyFrame{%
  \par\nobreak\offinterlineskip
  \vskip-\dimexpr\pgfkeysvalueof{/MyFrame/length} / 
  \pgfkeysvalueof{/MyFrame/factor} + 
  \dimexpr\pgfkeysvalueof{/MyFrame/length} / 
  \pgfkeysvalueof{/MyFrame/factor} - 
  \pgfkeysvalueof{/MyFrame/Vdist}\relax\noindent%
  \hskip-\pgfkeysvalueof{/MyFrame/Hdist}%
  \bgroup
    \color{\pgfkeysvalueof{/MyFrame/color}}%
    \rule{\pgfkeysvalueof{/MyFrame/length}}{%
      \pgfkeysvalueof{/MyFrame/thickness}}
    \hskip-\dimexpr\pgfkeysvalueof{/MyFrame/length} - 
    \dimexpr\pgfkeysvalueof{/MyFrame/length} / 
    \pgfkeysvalueof{/MyFrame/factor} - 
    \pgfkeysvalueof{/MyFrame/thickness}\relax%
    \rule[-\dimexpr\pgfkeysvalueof{/MyFrame/length} / 
    \pgfkeysvalueof{/MyFrame/factor} - 
    \pgfkeysvalueof{/MyFrame/thickness}\relax]{%
      \pgfkeysvalueof{/MyFrame/thickness}}{%
      \pgfkeysvalueof{/MyFrame/length}}
  \egroup
\egroup\par}

\makeatother

\usepackage{lipsum}

\begin{document}

\begin{MyFrame}
    \lipsum[1]
\end{MyFrame}

\begin{MyFrame}[length=1.5cm,thickness=2pt,Hdist=1.3cm,
  color=blue,factor=6,Vdist=8ex]
    \lipsum[1]
\end{MyFrame}

\end{document}

Answer 3

Use a key/value package like xkeyval, then define all your keys you want. They will get the value as #1:

\usepackage{xkeyval}
\makeatletter% not required in a package or class
\newlength\myframelength

\define@key{MyFrame}{length}{%
   \setlength{\myframelength}{#1}%
}
\define@key{MyFrame}{foobar}[default]{%
   \dosomething{#1}%
}
\makeatother

\newenvironment{MyFrame}[1][]{%
    \setkeys{MyFrame}{#1}% execute keys
    % ...
}{%
    % ...
}

% usage:
\begin{MyFrame}
  foo bar
\end{MyFrame}

\begin{MyFrame}[length=1pt]
  foo bar
\end{MyFrame}