Why are \listof{}{} and \listoffigures styled differently?

Question

I'm writing my thesis and I have certain code-snippets to show. I'm using the the listings package embedded in a custom float environment to display them.

To list them in an index at the beginning of my document - similar to \listoffigures - I use:

\listof{code}{List of Code}

This (technically) works as desired but looks completely different to my list of figures. See screenshot below (List of Figures on the left, List of Code on the right).

Why, and how to fix this? Or how to modify the \listof{}{} layout to look similar to the one of \listoffigures?

I tried this workaround which redefines the layout but it's not working as desired (still looks different) and is throwing more errors than I could post here.

Update 1: After some hours of trying to figure out of what wrong with my document (It's really bloated already.) I'll try to explain this with a minimal working example. Notice the screenshots below.

\documentclass[12pt,a4paper,twoside,openright]{report}
 \usepackage[english]{babel}
 \usepackage{float}
  \newfloat{algo}{tbp}{loa}[chapter]
  \setlength{\parskip}{3mm}     % !
  \setlength{\parindent}{3mm}   % !
  \frenchspacing
  \sloppy

 \begin{document}
  \listoffigures
  \listof{algo}{List of Algorithms}

  \chapter{foo}
   \begin{figure}
    \centering
    \rule{1cm}{1cm}
    \caption{A figure}
   \end{figure}
   \begin{algo}
    (algo)
    \caption{An algorithm}
   \end{algo}
   \begin{figure}
    \centering
    \rule{1cm}{1cm}
    \caption{Another figure}
   \end{figure}
   \begin{algo}
    (algo)
    \caption{Another algorithm}
   \end{algo}

  \chapter{bar}
   \begin{figure}
    \centering
    \rule{1cm}{1cm}
    \caption{Yet another figure}
   \end{figure}
   \begin{algo}
    (algo)
    \caption{Yet another algorithm}
   \end{algo}

 \end{document}

Parskip and parindent seem to play an important role, still I dont get a result as mentioned in lockstep's answer (with the spacing between chapters) ...

Update 2: Okay, now I found the reason why it's not working. It's the hyperref package. Updated MWE:

\documentclass[12pt,a4paper,twoside,openright]{report}
 \usepackage[english]{babel}
 \usepackage{float}
  \newfloat{algo}{tbp}{loa}[chapter]
%  \setlength{\parskip}{3mm}
%  \setlength{\parindent}{3mm}
  \frenchspacing
  \sloppy
% \usepackage{hyperref}                    % !!!
%  \hypersetup{pdftitle={Bachelorthesis}}  % !!!
%  \hypersetup{colorlinks=false}           % !!!
%  \hypersetup{plainpages=false}           % !!!
%  \hypersetup{pdfborder={0 0 0}}          % !!!
 \usepackage{etoolbox}
 \makeatletter
  \patchcmd{\@chapter}%
  {\addtocontents{lof}}%
  {\addtocontents{loa}{\protect\addvspace{10pt}}%
   \addtocontents{lof}}%
  {\typeout{*** SUCCESS ***}}{\typeout{*** FAIL ***}}
 \makeatother


 \begin{document}
  \listoffigures
  \listof{algo}{List of Algorithms}

  \chapter{foo}
   \begin{figure}
    \centering
    \rule{1cm}{1cm}
    \caption{A figure}
   \end{figure}
   \begin{algo}
    (algo)
    \caption{An algorithm}
   \end{algo}
   \begin{figure}
    \centering
    \rule{1cm}{1cm}
    \caption{Another figure}
   \end{figure}
   \begin{algo}
    (algo)
    \caption{Another algorithm}
   \end{algo}

  \chapter{bar}
   \begin{figure}
    \centering
    \rule{1cm}{1cm}
    \caption{Yet another figure}
   \end{figure}
   \begin{algo}
    (algo)
    \caption{Yet another algorithm}
   \end{algo}

 \end{document}

Uncommenting the hyperref package and settings messed up the layout of the custom \listof.

So to break down this issue:

1. How to adjust \parskip and \parindent without messing up the lists?
2. How to avoid hyperref package messing around with the layout?

Update 3: Closed this question:

1. How to adjust \parskip and \parindent without messing up the lists? I asked a follow-up question here: How to avoid \parskip being applied to \listoffigures etc.?
2. How to avoid hyperref package messing around with the layout? Solved: Simply loading hyperref at the end of all packages and after \makeatother.

Thanks to Frank Mittelbach's workaround which helped me to solve the layout issue till this point.

Answer 1

This is a fault of the floatpackage you might say. It defines the \listofcommand as follows:

\newcommand*{\listof}[2]{%
  \@ifundefined{ext@#1}{\float@error{#1}}{%
    \@namedef{l@#1}{\@dottedtocline{1}{1.5em}{2.3em}}%
    \float@listhead{#2}%
    \begingroup\setlength{\parskip}{\z@}%
      \@starttoc{\@nameuse{ext@#1}}%
    \endgroup}}

This means that it a) fixes the \parskip to zero (which would be usually ok but still somewhat questionable) and b) gives each "listof" line a hard-wired meaning, by defining \l@<type>. The values used are the default values for \@lfigure in the article class. However, if the class you use has different values (and it looks like it has) they are obviously not picked up.

Resolution: provide your own copy of \listof looking like this:

\makeatletter
\renewcommand*{\listof}[2]{%
  \@ifundefined{ext@#1}{\float@error{#1}}{%
    \expandafter\let\csname l@#1\endcsname \l@figure  % <- use layout of figure
    \float@listhead{#2}%
    \begingroup
      \setlength\parskip{0pt plus 1pt}%               % <- or drop this line completely
      \@starttoc{\@nameuse{ext@#1}}%
    \endgroup}}
\makeatother

This will make the formatting of the "list-of" lines the same as those for figures in the "List of Figures" listing and it will reset the spacing between paragrpahs (and each line here is a paragraph) to the default used by the article/report class. The alternative would be to take that setting completely out.

However, this is not quite enough in case report or book class is used. As mentioned in the answer by @lockstep the \chapter command also adds vertical space material to such listings. So in addition the \@chapter command needs to be patched to include this extra space. So you need something like

   \usepackage{etoolbox}
   \makeatletter
   \patchcmd{\@chapter}%
     {\addtocontents{lof}}%
     {\addtocontents{alg}{\protect\addvspace{10pt}}%  % <-- "alg" is the extension you use
      \addtocontents{lof}}%
     {\typeout{*** SUCCESS ***}}{\typeout{*** FAIL ***}}
   \makeatother

where you have to replace "alg" with whatever the file extension is that you use

Answer 2

The workaround you tried is for the book class which features a different defintion of \chapter. For report, the following works for me (i.e., yields identical formatting for the List of Figures and the newly defined List of Algorithms):

\documentclass[a4paper]{report}

\usepackage{float}
\newfloat{algo}{tbp}{loa}[chapter]

\usepackage{xpatch}
\makeatletter
\xapptocmd{\@chapter}{%
  \addtocontents{loa}{\protect\addvspace{10\p@}}%
}{}{}
\makeatother

\begin{document}

\listoffigures

\listof{algo}{List of Algorithms}

\chapter{foo}

\begin{figure}
\centering
\rule{1cm}{1cm}
\caption{A figure}
\end{figure}

\begin{algo}
(algo)
\caption{An algorithm}
\end{algo}

\begin{figure}
\centering
\rule{1cm}{1cm}
\caption{Another figure}
\end{figure}

\begin{algo}
(algo)
\caption{Another algorithm}
\end{algo}

\chapter{bar}

\begin{figure}
\centering
\rule{1cm}{1cm}
\caption{Yet another figure}
\end{figure}

\begin{algo}
(algo)
\caption{Yet another algorithm}
\end{algo}

\end{document}

Note: The screenshot you provided does not look like the default LoF spacing for the report class (there's additional spacing between entries located in the same chapter). You should provide a MWE showing the relevant packages and/or individual customizations.