“Double use” of a4paper (geometry/KOMA)?

Question

In my preamble, should I give the a4paper option just once or twice, i. e. once for the KOMA-script document class (scrartcl) and once for geometry? Is this redundant or does scrartcl need the option for the calculation of the type area (or something else)?

\documentclass[12pt,a4paper]{scrartcl}
\usepackage[a4paper]{geometry}

Lately, I have just used

\documentclass[12pt]{scrartcl}
\usepackage[a4paper]{geometry}

and I haven’t had any adverse effects. Still, it seems a little strange to me not to pass any “size options” to the document class. But is this the “right way” to go?

By the way, I am using XeLaTeX to typeset.

Answer 1

If you are using geometry you are overwriting the settings from typearea so the class doesn't need the option (btw a4paper or more precisely the option paper=a4 is the default anyway).

I personally don't use global options if possible to avoid unwanted side effects on packages. With local options it is easier to control which package gets which option.

Answer 2

As far as I know, global options, specified with the document class, will be passed down to the packages. So your global specification regarding paper size or language like ngerman for example will be used by any packages, where you could use this option too, like babel or csquotes.

Regarding a4paperin special, I think the KOMA-Classes already use this paper format by default, so it is not neccessarily needed as an option to the documentclass.

The option a4paper could be omitted with scrreprt, since this is a predefined setting for all KOMA-Script classes. See the KOMA Guide on p. 30.

So, in your case, you should be able to omit the a4paper alltogether without negative consequences, as it is already "preloaded".