Automatically-numbered affiliations using textual keys.

affils.sty

% affils.sty -- automatically number affiliations
% Copyright 2016 Peter Williams <peter@newton.cx>
% Licensed under the MIT License.
%
% To use:
%
% 1. Save this file next to your .tex file and add \usepackage{affils} at its top.
%
% 2. Before your author list, write:
%
%       \DeclareAffil{nickname}{Full text to appear.}
%
%    for each affiliation that might be used. Order doesn't matter. For example,
%
%       \DeclareAffil{cfa}{Harvard-Smithsonian Center for Astrophysics,
%          60 Garden Street, Cambridge, Massachusetts 02138, USA}
%       \DeclareAffil{nice}{All-Around Nice Fellow}
%
% 3. Instead of the \author command, use a new modified version like so:
%
%     \affilauthorlist{
%        P.~K.~G. Williams\affils{cfa,nice},
%        Your Name Here\affils{nice},
%     }
%
% 4. Enjoy! Affiliations will automatically be numbered and be listed in the order
%    used in the author list.

\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{affils}[2016/03/11 v0.1 affils (PKGW)]
\RequirePackage{kvsetkeys}

\newcounter{pkgwaffil@nextnum}
\setcounter{pkgwaffil@nextnum}{1}

\newtoks\pkgwaffil@texts
\pkgwaffil@texts={}

\newcommand\DeclareAffil[2]{\expandafter\newcommand\csname pkgwaffil@#1@text\endcsname{#2}}

\newcommand\affils@process@one[1]{%
  \expandafter\ifx\csname pkgwaffil@#1@text\endcsname\relax%
    \textbf{[unknown affiliation code #1!]}%
  \else%
    \expandafter\ifx\csname pkgwaffil@#1@num\endcsname\relax%
      % No number assigned -- do so and add to the list to emit
      \expandafter\xdef\csname pkgwaffil@#1@num\endcsname{\arabic{pkgwaffil@nextnum}}%
      \global\pkgwaffil@texts=\expandafter{\the\pkgwaffil@texts
        \altaffiltext{\csname pkgwaffil@#1@num\endcsname}{\csname pkgwaffil@#1@text\endcsname}}%
      \stepcounter{pkgwaffil@nextnum}%
    \fi
    % Add affil's number to the current list.
    \ifx\pkgwaffil@cur@numbers\relax
      \edef\pkgwaffil@cur@numbers{\csname pkgwaffil@#1@num\endcsname}%
    \else
      \edef\pkgwaffil@cur@numbers{\pkgwaffil@cur@numbers,\csname pkgwaffil@#1@num\endcsname}%
    \fi
  \fi%
}

\newcommand\affils[1]{%
  \let\pkgwaffil@cur@numbers\relax
  \comma@parse{#1}\affils@process@one
  \expandafter\altaffilmark\expandafter{\pkgwaffil@cur@numbers}%
}

% The trickiest part is that \author{} is not evaluated right off the bat, so
% \affils@process@one isn't actually called until the first piece of body text
% is encountered, which is too late for us to run the \altaffiltext commands.
% Therefore, we're gross and expand the author text into \@tempboxa, where we
% can evaluate the macros but not actually generate any text.
%
% We could just overwrite the \author command here, but I'm more comfortable
% explicitly giving it a new name.

\newcommand\affilauthorlist[1]{%
  \setbox\@tempboxa\vbox{#1}%
  \author{#1}%
  \edef\pkgwaffil@temp{\the\pkgwaffil@texts}%
  \pkgwaffil@temp
}