Sylvain Hubert schrieb am 04.11.2020 um 16:15:

Moreover, is there any way to let context give an error at all when encountering something like `\setuppagenumbering[position=footer]` ?

ConTeXt has a function to check assignment list for valid keys but 1. The function doesn't work with the normal setup command, 2. one has to register all valid keys 3. you can't create new keys on the fly which is used in a few styles and 4. it performance issues and leads to a noticeable performance drop. Wolfgang

Sylvain Hubert schrieb am 04.11.2020 um 22:10:

On Wed, 4 Nov 2020 at 21:32, Wolfgang Schuster mailto:wolfgang.schuster.lists@gmail.com> wrote:

4. it performance issues and leads to a noticeable performance drop.

This sounds a bit surprising, since intuitively it takes no less effort to deal with the registered key than to determine that a key is not registered.

There was never a real test for the performance but when you enable the checker in the example below (which works only with LuaTeX) the second list is slower. % engine=luatex \starttext \testfeatureonce{10000}{\getcheckedparameters[test][xx][a=b,c= d, e = f]} \enablecheckparameters \testfeatureonce{10000}{\getcheckedparameters[test][xx][a=b,c= d, e = f]} \stoptext Wolfgang