How can I use something like \vspace{\baselineskip plus 10pt}

Question

Is it possible to use \baselineskip with some extra glue inside of \vspace?

\documentclass{scrartcl}

\begin{document}
Text

\vspace{\baselineskip}
Works

\vspace{12pt plus 10pt minus 5pt}
Works

\vspace{\baselineskip plus 10pt minus 5pt}
Fails \dots
\end{document}

Answer 1

Since \vspace wants a "glue" as its argument and \baselineskip is a glue parameter, \vspace{\baselineskip plus 10pt minus 5pt} is incorrect; the easiest way is to say

\vspace{1\baselineskip plus 10pt minus 5pt}

as 1\baselineskip will make it into a simple dimension, discarding its possible plus and minus components.

Usually \baselineskip has zero stretching and shrinking components. If one wants to be on the safe side and add 10pt to the stretch and 5pt to the shrink components whatever they are, the "correct" way is

\vspace{\glueexpr\baselineskip + 0pt plus 10pt minus 5pt\relax}

Note: \vspace{\dimexpr\baselineskip plus 10pt minus 5pt\relax} works because when TeX scans for the \dimexpr it arrives to the p that cannot be part of a dimension expression and stops the scanning, having already converted \baselineskip to a dimension discarding the stretch and shrink components. So the final \relax is not the delimiter of \dimexpr and will go into the input stream (where it probably does no harm).

Answer 2

use dimexpr for adding the skips

\vspace{\dimexpr\baselineskip plus 10pt minus 5pt\relax}