@UlrikeFischer -- Never been a pirate, but in a former life, I used to hang around with some crazy fencers. Have also known a number of reenactors. Learned quite a lot about medieval armory too. Even knew someone whose hobby was fabricating chain mail by hand. (He'd work on it in the same situations I would indulge in knitting, including attending lectures.)
@Skillmon write the documentation, prove the specification is correct, then automatically derive the implementation from the documentation. Problem solved.
@DavidCarlisle well the question is if \input should do something like \def\protect{}. The error message File protecttest-input.tex' not found. looks rather odd.
@UlrikeFischer I don't get an error message (I have a file of that name) But yes it could do something with \protect but it has to be very late, if you disable \protect too early commands that are made robust will just blow up.
@UlrikeFischer well I also have a file called protect{begingroup1endgroupover2}.tex
@UlrikeFischer and if that didn't have protect at the start would that be a better "filename string" for input of \frac{1}{2} ?
@UlrikeFischer well that's what I meant in the gh issue. there is an automatic error free conversion of \blub to a "filename string" whether or not it's the string you wanted is a matter of personal judgement not a given clear cut rule.
On names of expl3 functions: If I create a function that takes as input a token list variable and another N-type argument (a decision function), but doesn't modify the variable but instead leaves the result in the input stream inside of \unexpanded, should it be named \tl_<name>:NN or \tl_<name>:oN? It can't be V, as it requires the variable to expand in one step with \exp_after:wN.
Same problem with a clist (with the resulting clist being left in the input stream, rather than modifying an existing variable), what would be the correct name?
@Skillmon Well yes but that's an internal detail: conceptually, \tl_<name>:NN in these cases is really just a convenience over only providing \tl_<name>:nN then leaving it to the user to create/use \tl_<name>:VN
@Skillmon Point is that if you specify #1 must be a tl var, then the signature is N-type
@Skillmon Like I say, if you document that the argument must be a variable, then it must be N-type. Or you just document \tl_<name>:nN, provide the o-type variant and leave it at that
Another stupid question regarding expl3: If I add a function that sorts a comma list, but without altering the list, but leaving the result in the input stream (still in clist notation, so that it could, for example, be used inside of a \clist_map_function:nN or similar), in which section should this be put in the documentation?
Hmmm, this tex.stackexchange.com/questions/580206/… is interesting: latex knows the size of the pictures it is including, so maybe it's possible to tell it to use for example imagemagick to resize them to 150dpi or something like that?
@UlrikeFischer No, I explained myself badly. If you include something as, say, \includegraphic[width=0.5\linewidth]{file.jpg} and you want to have the image in the final document at 150dpi, you need to know the final size of the image to scale it. This info is known just to LaTeX, it's not in the image.
That's basically what gs do when you use -dPDFSETTINGS=/ebook to reduce PDF sizes after-the-fact....
@Rmano well yes, if you want a specific dpi you will have to record somehow their target width, but that you could rather easily write to some file to create a suitable batch file.
@UlrikeFischer yes, that could be an idea. If the log file has something like "including image.jpg at 2.3in x 1.6in" then you can process it, resize the whole lot (once!) and then be happy.
@DavidCarlisle that's what I do when I prepare the list of students with photos for the labs --- I know the final size and so I resize them all while fetching from the database. But maybe there are cases when the size changes --- hmmm --- maybe include the photos in X tabularx cells? (that would be evil...)
@DavidCarlisle -- Is this in reference to the meta question about blank lines in math? I'm going to look to see if there's a good question about that listed in the math section of "often referenced questions. But I have to run an errand right now. Back in maybe half an hour.