Where to start with creating a new package?

Question

I want to create a new LaTeX package to assist myself, and other researchers working in the same field typeset their work. Currently, it is primarily done manually per paper, and while that mostly works, it's clunky, slow and a bit error-prone.

My online searches have turned up various tidbits (along with hats), most notably Overleaf's advice, the LaTeX2e for class and package writers document and documents on LaTeX3's expl3 and xparse packages. It's not clear to me which one of these I should follow. LaTeX2e for class and package writers seems like the obvious place, but it's about 14 years old now. Meanwhile, I know LaTeX3 is coming, and I would prefer the package to be 'future-proof', but I can't tell if it's what I should start with at this point (nor, to be honest, which one of the aforementioned packages is the one I should be looking at).

I could only find a few questions on here that seemed relevant (namely, this, this and this) and all of them more-or-less dive in a bit ahead of where I am at.

So, my question is, where should I start with creating a brand new LaTeX package, in this day-and-age? Have I missed some important guides/advice somewhere? I would prefer it if I could make sure that this package can be used with any of the LaTeX distributions and engines.

Answer 1

Since nobody else ever posted an answer, I thought I should put one up, just in case somebody stumbles across this question. This answer deals only with packages since that is what I needed. I don't know about writing classes.

Firstly, I would say: Do you really need to create a new package? Is there definitely no pre-existing package you can use? Do you only have a few lines of custom commands, such that it isn't worth the effort?

If you just want to write up a few commands, then checking the Overleaf advice, LaTeX2e for Class and Package Writers and the LaTeX Wikibook's pages on it are probably the best starting place, and perhaps all you will need. If you can access a copy of it, it would be worth also taking a look at The LaTeX Companion (2nd ed), specifically Chapter 14 and Appendix A (it's available in O'Reilly's online learning system, if you use that).

If, on the other hand, you are wanting to create a full-blown package with supporting documentation, especially if you want to contribute it to CTAN, then your best bet is probably to use the .dtx approach, which is arguably a de facto standard these days. This essentially involves creating a special file which includes both the commands themselves, and also the documentation to support them. The use of dtx files is much too big a topic to describe in this post, so instead, I will include a bunch of links that may be of help:

• The dtx tutorial.
• A brief dtx FAQ.
• A blog post about an example dtx file.
• The documentation for the doc LaTeX class, the backing class for this system.
• The documentation for DocStrip, which is the part that pulls your commands out of the dtx file and puts them into a sty file.
• sty2dtx or makedtx, Perl scripts to extract what you have out of a sty file and make it a proper dtx file.
• The dtx Gallery, which contains a handful of sample dtx files - though they're all quite old now.
• These questions about preparing packages for upload to CTAN (I found them well after I posted this question).

Almost certainly, there are other good resources out there, but these were the ones I found and which helped me with my task.

In the end, I completely abandoned the idea of using LaTeX3 for now, since I couldn't find anything that provided a nice introduction to it, instead of appearing to be reference material for those who are already knowledgeable about it. I imagine there are good resources out there, but I didn't locate them.