Hello, [\unexpanded vs \detokenize]
Well, currently it makes a difference, three actually:
1. \unexpanded introduces "IMPOSSIBLE."
Hm.
Addition: Only in the very specific situation created by the format weird_format.tex (see my mail from 09:06 this morning).
2. \unexpanded introduces spaces after control sequences.
Why wouldn't \detokenize do the same? Wait, it does:
At least in the context of \directlua. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
I guess that this may be the real reason.
I thought a bit about this, and I think that it is quite useful if \detokenize does not introduce spaces when used in \directlua, as opposed to \unexpanded, since sometimes (i.e. when used as a set in lpeg.S) spaces are completely undesired. Of course, in these situations \string could be used as an alternative. But since \detokenize is equivalent (at least as I understand it) to prefixing each token with \string, \detokenize should not introduce spaces. IMO.
btw, if you change \unexpanded by \detokenize you get the desired result
I know.
Oops. Why would that be?
Because of a bug? :-)
I should think so. Not sure whether this behavioral difference is intended, but it certainly feels wrong to me.
I think we are talking about slightly different things: You about the introduction of spaces by \unexpanded and \detokenize, me about the "IMPOSSIBLE.". The latter most certainly is a bug :-)
-- David Kastrup, Kriemhildstr. 15, 44793 Bochum
Jonathan