Difference between commenting out empty lines and \noindent?

Question

My question is similar to this one but I understand the behavior described there and am interested in best practices in cases like the following.

Typically, when ending an environment like quote in the body of my documents, I've always left a blank line after the environment (it improves code readability for me to separate environments from the main text in this way) and suppressed the paragraph indentation with \noindent. Like so:

\documentclass{article}

\begin{document}

Some body text. Let's introduce a quote:%
%
\begin{quote}
Some quote text.
\end{quote}

\noindent Some text following the quote.

\end{document}

Now, I recently realized (no idea why it took me so long) that I could simply comment out the empty line and save myself from littering a bunch of \noindents all over my document. So now I do this:

\documentclass{article}

\begin{document}

Some body text. Let's introduce a quote:%
%
\begin{quote}
Some quote text.
\end{quote}
%
Some text following the quote.

\end{document}

What I am interested in now is whether there are any substantive differences between the two approaches given above that might lead me to prefer one over the other (this is in the spirit of some of my recent questions like inline math or \textit for author defined math constants). Are there?

Answer 1

Yes there is a lot of difference, and use of \noindent is usually a sign that something is wrong:-)

A blank line denotes the start of a paragraph.

So if you want the text after the display environment (quote enumerate center displaymath all work the same) to be part of the same paragraph then you should not have a blank line, if you do want a new paragraph then you should have a blank line.

Practically speaking a new paragraph is marked by several things: extra vertical space, and indentation and \noindent only hides some of the things, the indent, but even if it hid everything (and if \parskip is zero it does hide most) it would still be the wrong thing to do and complicate conversion to other formats that may want paragraphs fully marked up.

Answer 2

I my eyes the difference is that a blank line ends a (logical) paragraph of your text, which should be represented in the source code as well. I try to prevent using \noindent but I use out commented empty lines to make the source more readable – as in your second example.

Furthermore if you sometimes decide to switch from indenting paragraphs to separating them, the \noindent approach will fail … so uncommenting is more robust …