On 2022-05-28 2:27 a.m., Stefan Nedeljkovic wrote:
> One slight problem is when I use 2\measured{xheight} as the font size I
> get an error. \measure works fine though.

The old version expected direct input, not a \dimen. Try this:

     \starttexdefinition setxheight [#1][#2]
         \switchtobodyfont[#1, 12pt]
         \scratchdimen=\dimexpr#2\relax
         \switchtobodyfont[#1, \cldcontext{tex.dimen.scratchdimen / tex.sp"1ex" * tex.sp"1em" .. "sp"}]
     \stoptexdefinition

     \definemeasure[xheight][2.5pt]

     \starttext
         \setxheight[adventor][10\measured{xheight}] Hello!
     \stoptext


-- Max