Specific footnote style in memoir

Question

I have implemented the following style for my footnotes in memoir

\documentclass{memoir}

\usepackage{lipsum}
\usepackage{calc}

\setlength\footparindent{1.2\parindent}

\newlength{\foothelp}
\newlength{\foothelpextra}
\footmarkstyle{%
\setlength{\foothelp}{\footparindent}%
\setlength{\foothelpextra}{\widthof{\textsuperscript{#1}}}%
\addtolength{\foothelp}{-\foothelpextra}%
\textsuperscript{#1}\hspace{\foothelp}%
}


\begin{document}
\lipsum[1]\footnote{\lipsum[1]

\lipsum[1]}

\setcounter{footnote}{999}\footnote{\lipsum[1]

\lipsum[1]}
\end{document}

But if I change the font size I need to manually adjust the \footparindent. Is there a better way of implementing this style? Moreover, is it possible for the indent in the footnotes to match the indent in the body text? This style is very much like in this question:

Adjust footnote indentation in memoir

The difference is that the footnote mark should be flushleft.

Edit: Added a picture displaying the style. As can be seen all the indents doesn't quite match up.

Answer 1

Is this what you are looking for?

\setlength{\footmarkwidth} {0em}
\setlength{\footmarksep}   {0em}
\footmarkstyle{\makebox[\footparindent][l]{\textsuperscript{#1}}}

Set \footparindent to \parindent proper to have them line up.

In this MWE the \XXX is just an easy way to show the alignment, it is designed to not disturb.

\documentclass{memoir}

\usepackage{lipsum}

\setlength\footparindent   {\parindent}
\setlength{\footmarkwidth} {0em}
\setlength{\footmarksep}   {0em}
\footmarkstyle{\makebox[\footparindent][l]{\textsuperscript{#1}}}


\newcommand\XXX{\llap{\smash{\rule[-\paperheight]{0.1pt}{2\paperheight}}}}

\begin{document}
\lipsum[1]\footnote{\lipsum[1]

\lipsum[1]}

\setcounter{footnote}{999}\footnote{\XXX\lipsum[1]

\lipsum[1]}
\end{document}

Answer 2

Like this?

\documentclass{memoir}

\usepackage{lipsum}
%\usepackage{calc}

\footmarkstyle{%
  \makebox[\parindent][l]{\textsuperscript{#1}}%
}
\setlength{\footmarkwidth}{0pt}
\setlength{\footmarksep}  {0pt}
\setlength{\footparindent}{\parindent}

\begin{document}
\lipsum[1]\footnote{\lipsum[1]\lipsum[1]}

\setcounter{footnote}{999}\footnote{\lipsum[1]\lipsum[1]}
\end{document}