Bassically the idea is that you use a new autowidest key instead of widest=<string>, and it works out the <string> for you by using two LaTeX runs. Unfortunately this adds the eqparbox package as a dependency.
Here's a stupid example showing that unlike the stackexchange code above, my code will handle user suplied align and format keys, it also works with the usual =* option, instead of neading you change it to =! option.
\newcommand{\myformat}[1]{(#1)} % Put the label in parantheses
\SetLabelAlign{testy}{\hfil#1:} % A right aligned label with a : after it
\setlist[description]{labelsep = 0.5em, labelindent = 1em, leftmargin = *, align=testy, format=\myformat, autowidest}
\begin{description}
\item[a label] some text\\
more text
\item[realy long label] some test\\
more text
\item[another label] some test\\
more text
\end{description}
The above will roughly come out as:
(a label): some text
more text
(realy long label): some test
more text
(another label): some test
more text
Note: I delete an example use case in the manual for \EnumitemId since it is now redundant (autowidest is much better as it doesn't assume the last label is the widest).
This adds the feature request by #3 . I based my code of the answer here https://tex.stackexchange.com/a/547398.
Bassically the idea is that you use a new
autowidestkey instead ofwidest=<string>, and it works out the<string>for you by using two LaTeX runs. Unfortunately this adds theeqparboxpackage as a dependency.Here's a stupid example showing that unlike the stackexchange code above, my code will handle user suplied
alignandformatkeys, it also works with the usual=*option, instead of neading you change it to=!option.The above will roughly come out as:
Note: I delete an example use case in the manual for
\EnumitemIdsince it is now redundant (autowidestis much better as it doesn't assume the last label is the widest).