I would have thought .tr would be of use here, but I can't get it to translate a space to something else, probably due to how its arguments are parsed. (It doesn't strip off a leading double quote, of course.) Cursory experiments with .char didn't seem to work either.
So I tried manually replacing spaces with the Unicode character U+2423 (OPEN BOX): ␣ (if that shows up in your mail client). I remember seeing spaces represented with a similar glyph in various sources. That character is not in the Courier font, but is in DejuVuSansMono, so I installed the DejaVu fonts (thanks to Peter Schaffter's install-font.sh <https://www.schaffter.ca/mom/mom-06.html#install-font> script) and that worked ok. It should be possible to run the tbl source of your tables through a script that substitutes the OPEN BOX character for all spaces. I was going to suggest that the script change tabs into the Unicode Character CIRCLED LATIN CAPITAL LETTER T, but that's not in DejaVuSansMono. (Lesk used a T overstruck on a circle.) And then I got to thinking: If you want something in Courier (so as to not have to install a font), you might try substituting Unicode Character WHITE CIRCLE for spaces and WHITE SQUARE for tabs. That is not mnemonic as the circled T and OPEN BOX, alas. Or you could use the groff characters \[ci] and \[sq]; that would probably be easier than messing with Unicode characters. Or you could try overstriking S and T on \[ci], although when I try that the result has the bottom of the S and T over the bottom of the circle. Anyway, here's the test document I used: .na .LP This is a paragraph. .LP DejaVuSansMonoR: .br .ft DejaVuSansMonoR This␣is␣a␣sentence. .br What␣to␣do␣now? .br .LP Courier: .ft C .br This○is□a◊sentence with Unicode WHITE CIRCLE, and WHITE SQUARE. .br This\[ci]is\[sq]a\[ci]sentence with groff characters \\[ci], and \\[sq]. .LP Using "\fC.char \\[overstrucks] \\o'\\[ci]\\s[-4]S\\s0'\fP", etc. .br .char \[overstrucks] \o'\[ci]\s[-4]S\s0' .char \[overstruckt] \o'\[ci]\s[-4]T\s0' .ft C This\[overstrucks]is\[overstruckt]a\[overstrucks]sentence with overstruck characters and .char. .LP This is a paragraph. and here is what the output looks like: [image: image.png] Does anybody have other ideas? On Fri, Jun 18, 2021 at 9:16 AM Oliver Corff <oliver.co...@email.de> wrote: > Hi, > > I thought over the subject and I decided to write a new introduction to > tbl, akin to Lesk's introduction, but under FLOSS license and with a > focus on the gnu extensions. > > For this purpose, I have one obviously uninformed and stupid question. > How do I show code examples in groff (I think I'll opt for the ms macro > set) with the whitespace character 0x20 marked, akin to the \verb*|...| > command in LaTeX? \verb|...| produces the included text in tt courier > (or another fixed-pitch font suitable for displaying code) with spaces > shown as blank, whereas \verb*|...| inserts a special symbol for every > 0x20 character. > > Does the ms macro package feature an environment for displaying source > code, or do I mimick that with font and margin settings? > > Since my introduction will demonstrate things like nospaces, tab > settings etc., it would be nice to show the spaces in the source code. > > Thanks a lot, and I am happy to take the beating if this question > demonstrates that I was the last one to ask. > > Oliver. > > > On 17/06/2021 18:46, G. Branden Robinson wrote: > > Hi, Oliver! > > > > At 2021-06-15T12:39:02+0200, Oliver Corff wrote: > >> my huge text project which involved typesetting approx. 1,300 tables, > >> tiny, small, large and huge, demonstrated that tbl is a remarkably > >> powerful and reliable tool for this work, and I can say with > >> confidence that the question which type of table software to use > >> (LaTeX? (x)html? others?) was best answered by tbl which helped me > >> recreate tables with a fidelity so close to the printed sources that > >> the uninitiated reader could not tell an image of the page from the > >> typeset reproduction. > > That's excellent news! > > > > What is the copyright licensing status of these 1,300 tables? Is there > > a chance we could get a small, potentially simplified subset of them > > under a FLOSS license so that we could use them to illustrate GNU tbl's > > feature set? An excellent property of Lesk's tbl paper was the suite of > > examples, but we don't have that document in our distribution and the > > few examples in our tbl(1) man page compare poorly. > > > > Speaking of the feature set, how much of GNU tbl's feature set do you > > figure you ended up exercising by the end of this project? Was there > > anything that you expected to use but ended up not needing? > > > >> I came across a few very minor discrepancies between expected and > >> actual behaviour, though. > >> > >> 1) For the global option "tab(x)", the man page says: > >> > >> tab(x) Use the character x instead of a tab to separate items in a > >> line of input data. > >> > >> This works as long as x is a 7-bit ascii character, it does not work > >> with utf-8 characters. E.g.: "tab(|)" (with the pipe symbol) works, > >> "tab(¦)" does not work and yields the message: "argument to `tab' > >> option must be a single character". > >> > >> I suggest either specifying "7-bit ascii character" in the manpage > >> and/or make the tbl parser utf8-aware. > > Hmmm, yes--since tbl parses the table for itself, *roff special > > character escapes will not serve as a workaround. And UTF-8 support > > would be a significant undertaking. > > > > I've filed this as <https://savannah.gnu.org/bugs/?60790>. > > > >> 2) The global option "nospaces", according to the manpage, is > >> described as: > >> > >> Ignore leading and trailing spaces in data items (GNU tbl only). > >> > >> The following point may be a question of correct interpretation of > >> this statement. Does the underbar "_" qualify as a data item in this > >> terminology? I positively think so, because the manpage states > >> > >> If a data line consists of only ‘_’ or ‘=’, a single or double > >> line, respectively, is drawn across the table at that point; > >> > >> If my data line consists of a single '_', that line is drawn. However, > >> if that '_' is followed by spurious whitespace, then only the '_' > >> appears in the first cell, and no line is drawn, or a line spanning > >> the first cell only is drawn. From a logical point of view, this is > >> clear, as the statement says "consists of only ...", but the nospaces > >> option does not seem to work here as expected. > > Doug's follow-up to this point seems reasonable. For me, it reinforces > > the principle I espouse that diligent management of one's lexicon is one > > of the most important things you can do in a software project. > > > > When revising the tbl(1) man page in the future, I will attend closely > > to the uses of the terms "data line" and "data item", and try to make > > sure they're correct and consistent. > > > > I once got partway through a rewrite of tbl(1) (the page) once, with > > much terminological alteration around "global option", "column > > specifier", and "column modifier". I disfavor the term "global option", > > because "global" options don't persist beyond a .TS/.TE table region, > > not even in the same document. I don't think novice users' concept of > > something "global" stops anywhere short of the entire file they're > > editing. > > > > I ran out of steam on that project because there was just too damn much > > I wanted to fix about the man page. Not having a separate document (as > > AT&T tbl had) to point the user to for practical examples was a major > > problem, hence my request above. Coming up with a good suite of > > examples is itself a significant undertaking, and while I found the > > examples contributed by Bernd to be contrived and meager, I couldn't > > honestly say that they weren't better than nothing. > > > > In my ideal world, tbl(1) would describe the syntax of the command and > > its input (or the latter could be migrated to a tbl(7) page--I suspect > > that would win Ingo's support and it wouldn't bother me at all), and > > we'd have a separate tbl.ms document chock full of source alongside > > rendered examples for users to emulate, experiment with, and build > > their expertise with. > > > > Regards, > > Branden > > -- T. Kurt Bond, tkurtb...@gmail.com, https://tkurtbond.github.io
