Remap heading commands

Question

I am writing a pair of Pandoc template and LaTeX package(s) for my authoring workflow (write in Markdown, produce PDF through Pandoc->LaTeX). In the Markdown document the type of document can be selected, and consequently different document classes can be loaded (book, report, article, presentation, or letter classes).

Unfortunately I can't make Pandoc dynamically adjust the mapping of heading levels to LaTeX commands. So the intermediate LaTeX file will always have \section{} as first-level headings, \subsection{} as second level etc., as it is appropriate for an article class.

What I can do in a Pandoc template is conditionally execute LaTeX commands, so the suggestion was to remap the LaTeX sectioning commands appropriately. My question is: is it possible to "remap" all sectioning commands or do I have to "recreate" them by copying their original definition?

If I do

\renewcommand{\chapter}[1]{\part{#1}}

it seems to correctly shift chapters to become parts. However, if I do

\renewcommand{\chapter}[1]{\part{#1}}
\renewcommand{\section}[1]{\chapter{#1}}

both sections and chapters end up being parts. I can see why this happens, as \section is mapped to \chapter which is already a \part (the order of the two commands doesn't seem to make a difference, which is what I hoped for).

What is the best (only?) way of shifting all heading levels by a fixed number of levels?

Answer 1

Start from the lowest sectioning level you plan to use:

\let\subsubsection\subsection
\let\subsection\section
\let\section\chapter
\let\chapter\part

With \let one essentially copies the current definition.

Answer 2

You can tell pandoc to use part as the top level with the option --top-level-division=part

From pandoc's user guide:

--top-level-division=[default|section|chapter|part]

Treat top-level headers as the given division type in LaTeX, ConTeXt, DocBook, and TEI output. The hierarchy order is part, chapter, then section; all headers are shifted such that the top-level header becomes the specified type. The default behavior is to determine the best division type via heuristics: unless other conditions apply, section is chosen. When the LaTeX document class is set to report, book, or memoir (unless the article option is specified), chapter is implied as the setting for this option. If beamer is the output format, specifying either chapter or part will cause top-level headers to become \part{..}, while second-level headers remain as their default type.