Try to comment only where really necessary; the code should try to be self-documenting whenever possible.

That being said, the placement can depend: If you use a separate line for the comment, put it before the actual code. If you have it on the same line, put it after.

// this workaround is required to make the compiler happy
int i = 0;


Vs.

int i = 0; // make the compiler happy


But never:


int i = 0;
// this workaround is required to make the compiler happy




Comment before or after the relevant code
I need to have footnotes in captions of figures and therefore use the afterpage package to keep the footnotes and the figure on the same page (also using package footnote for footnotes in figures). I need to write my PhD thesis in a style that was defined in Word, but I wanted to write in Latex. Word always puts footnotes at the bottom of the page. So basically, I'm forced to put footnotes at the bottom. Others seem to have the same problem (other question, accepted answer puts footnote on bottom of page, but is manual; also for tables that might float and floats in general, where I found the idea with afterpage; also in other places on the web), so I though I might share my progress made so far and get input from others on the issue.

When using floats in an afterpage environment, the ordering of the footnotes at the bottom gets mangled up in some parts of the document. I managed to fix the ordering of the footnotes at the bottom with a dirty hack (see below), but the footnote number of the figure is not always the first footnote number appearing on the page. So I now have basically two questions:


What does my dirty hack do? I just tried some things and somehow it worked, now I'd like to understand why and whether it might have effects on other parts of the document.
How can I get the correct footnote number, i.e. the lowest footnote number on that page, for the footnote of the caption?


My dirty hack (using \patchcmd from etoolbox): 

\usepackage{etoolbox}

\makeatletter
\tracingpatches
\patchcmd{\AP@savetop}{\global\setbox\AP@footins\box\footins}{}{}{}
\patchcmd{\AP@@}{\insert\footins{\unvbox\AP@footins}\fi}{\setbox\footins\vbox{\unvbox\AP@footins}\fi}{}{}
\makeatother


What I get without my dirty hack:


  
  Footnotes on same page as figure
  Footnotes order not correct
  Footnote number of caption not first number on page
  




What I get with my dirty hack


  
  Footnotes on same page as figure
  Footnotes order correct
  Footnote number of caption not first number on page
  




What I want


  
  Footnotes on same page as figure
  Footnotes order correct
  Footnote number of caption first number on page
  


MWE:

\documentclass[12pt,a4paper,twoside,openany,fleqn]{book}

\usepackage{afterpage}
\usepackage[ngerman]{babel}
\usepackage{lipsum}
\usepackage{footnote}
\makesavenoteenv{figure}

\begin{document}
\chapter{First Chapter}

\lipsum[1]\footnote{Footnote}
\afterpage{
    \begin{figure}[htp]
        \fbox{Hello World}
        \caption[test]{test\protect\footnote{Test}}
    \end{figure}
}
\lipsum[1]\footnote{Footnote}
\lipsum[1]\footnote{Footnote}
\lipsum[1]\footnote{Footnote}
\afterpage{
    \begin{figure}[htp]
        \fbox{Hello World}
        \caption[test]{test\protect\footnote{Test}}
    \end{figure}
}
\lipsum[1]\footnote{Footnote}
\lipsum[1]\footnote{Footnote}

\end{document}


Edit1:
Second MWE without afterpage, where footnote is kept on different page. Adding afterpage around the figures moves the footnote to the correct page:

\documentclass[12pt,a4paper,twoside,openany,fleqn]{book}

\usepackage[ngerman]{babel}
\usepackage{lipsum}
\usepackage{footnote}
\makesavenoteenv{figure}

\begin{document}
\chapter{First Chapter}

\lipsum[1]\footnote{Footnote}

    \begin{figure}[tp]
        \begin{minipage}[t][0.4\textheight][t]{0.6\textwidth}
                \end{minipage}
        \caption[test]{test\protect\footnote{Test}}
    \end{figure}

\lipsum[1]\footnote{Footnote}
\lipsum[1]\footnote{Footnote}
\lipsum[1]\footnote{Footnote}

    \begin{figure}[tp]
        \begin{minipage}[t][0.4\textheight][t]{0.6\textwidth}
    \end{minipage}
    \caption[test]{test\protect\footnote{Test}}
    \end{figure}

\lipsum[1]\footnote{Footnote}
\lipsum[1]\footnote{Footnote}

\end{document}




