## Thursday, August 25, 2011

### Using \gobblepars to prevent LaTeX from adding empty lines at gaps

While searching for something else, I came upon a StackOverflow question from a while ago that asked how to prevent LaTeX from adding a \par at particular blank lines in the source code. The asker didn't want to remove blank spaces everywhere; he just wanted to get rid of the paragraphs at certain spots.

Of course, you can use comments to do this:
\somemacro{}
%
Some text
However, a lot of people don't like the look of that. Some of the responders on StackOverflow gave some alternatives that seemed ugly and half baked. So I came up with \gobblepars, which is a macro you can add to the end of your own macro definitions to cause them to eat up all trailing pars, or you can use explicitly. For example:
\somemacro{}\gobblepars

Some text
would do the same as the commented stuff above. Moreover, if you had control over \somemacro, you could build \gobblepars into it (in fact, even if you didn't have control, you could use \let and \def to augment an existing macro with a trailing \gobblepars, but that's a different topic).

Here's the simple definition of \globblepars (you put this in the preamble of your LaTeX document):
\makeatletter
\newcommand\gobblepars{%
\@ifnextchar\par%
{\expandafter\gobblepars\@gobble}%
{}}
\makeatother
So that's pretty simple. It checks for a \par (which includes a blank line in the source) trailing it. If it finds one, it gobbles it up (i.e., gets rid of it) and then calls itself again. This process will continue until it finds something other than a \par. Hence, it "gobbles" strings of "pars".