Macros for common abbreviations

Question

Common abbreviations are surprisingly tricky to format correctly. I'd like some simple macros for them, to be used like so:

You should eat more fruit, \eg apples, bananas, oranges, \etc.

There are (at least) three (interrelated) problems to overcome in defining this:

1. If used at the end of a sentence, we end up with doubled-up periods. Simply leaving off the period in the macro seems ugly (especially for things like 'e.g.', 'i.e.', ...). A better solution calls for something like \consumeif{.}, but I can't find a beast.
2. The macro should include the behavior of \xspace.
3. It should also produce correct spacing depending on whether it ends a sentence, like the logic of \@.

How would I (you) write such a macro? Note: I'm aware of this question and others like it, but the answers don't resolve my problems.

Answer 1

I think the \eg and \ie macros should be defined differently to \etc, because they will never be at the end of a sentence. You can simply use \@\xspace at the end to ensure a space with the correct width if one is required. For \etc you can use \@ifnextchar{.}{<yes>}{<no>} to check for a following full stop.

\documentclass{article}

\usepackage{xspace}
\newcommand*{\eg}{e.g.\@\xspace}
\newcommand*{\ie}{i.e.\@\xspace}

\makeatletter
\newcommand*{\etc}{%
    \@ifnextchar{.}%
        {etc}%
        {etc.\@\xspace}%
}
\makeatother

\begin{document}
\noindent
You should eat more fruit, \eg apples, bananas, oranges, \etc. Next sentence.

\noindent
You should eat more fruit, \eg, apples, bananas, oranges, \etc but also tomatoes.

\end{document}

Answer 2

Phil Ratcliffe has recently posted to CTAN two packages to deal with this question:

• xpunctuate “provides the commands \xperiod, \xcomma and \xperiodcomma, which follow a similar procedure to that of \xspace, and insert punctuation if and only if it is necessary,” and
• foreign which, among other things, uses the commands from xpunctuate to define \eg and \ie as the OP requests.

These commands attempt to correctly handle sentence spacing via a simple convention, better illustrated than described:

• “The forest is filled with lions, tigers, bears, \etc.” becomes
  “The forest is filled with lions, tigers, bears, {\em etc}.”
• “The forest is filled with lions, tigers, bears, \etc!” becomes
  “The forest is filled with lions, tigers, bears, {\em etc}.!”
• “Lions, tigers, bears, \etc fill the forest.” becomes
  “Lions, tigers, bears, {\em etc}.\@ fill the forest.”

(Actually, the font selection is a bit more complicated than I’ve shown.)

There’s even code that inserts a comma after mid-sentence \ie & \eg. (This comma can be disabled via the [UKenglish] option.)

Answer 3

After reading @J. C. Salomons answer I think xpunctuate is suited best for this task. Since I do not need the extra functionality from the foreign package, I decided against using that one.

The implementation of the macro provided by the package was not trivial for me, so I expect others might struggle with this as well. Here is my definition of an \eg macro, using the xpunctuate package (make sure to load it in the preamble):

\providecommand{\eg}[0]{e.g\xperiod}

Explanation:

• \providecommand defines a new macro if the macro name is not already used. Otherwise it will issue an error. I choose this to not unknowingly overwrite an important macro of a different package which might break its functuality.

• This is followed by the macro name: {\eg}

• Then the number of arguments is defined, in this case [0]. This is optional, however I like to make it explicit.

• Last, the macro is defined. It consists of e.g, followed by xpunctuate's macro \xperiod. This will insert a period and an interword space if the macro is followed by another word, a period and no space if it is followed by punctuation and nothing if it is followed by a period, i.e. at the end of a sentence.

This should handle all different usecases for abbreviations correctly.