Hello all,

I'm taking a look at how to begin on siunitx in expl3, and I've already
found something I'm stuck with.  The code I have at present is essentially:

\def\example#1{
  \begingroup
    \makeatletter
    \@makeother{\,}%
    \@makeother{\.}%
    \@makeother{\+}%
    \@makeother{\-}%
    \def~{}%
    \def\,{}%
    \catcode`\~=\active\relax
    \catcode`\^=\active\relax
    \catcode`\_=\active\relax
    \everyeof{\noexpand}%
    \endlinechar\m@ne
    \protected@xdef\storage{\scantokens{#1}}%
  \endgroup
}

which results in \storage containing an expanded copy of #1, with any
hard spaces (~ and \,) removed.  This may not be the best way, but it
works.  (In siunitx, see \si@num for the context of this).

In expl3, I can only find \scantokens, \everyeof and \endlinechar in the
:D range, so these are out.  I'm guessing that I should do things a
different way, but could do with enlightenment.  Does no-one want
\scantokens?
-- 
Joseph Wright