[latexrefman] latex-info Lengths

Vincent Belaïche vincent.belaiche at gmail.com
Tue Jun 5 06:15:51 CEST 2018

Hello Jim,

I fully agree that this is a LaTeX manual, not a TeX manual.

My point was that if \day, \month and \year are documented in the
manual, then we should explain why the user can't format them like
\theday or \Roman{day} because these are not LaTeX counters — the
current text is unclear to that extent.

Or rather we should say that one never needs to use them directly as
there are packages like datetime2 to provide the formatting that one
needs. And if none of the formats of datetime2 are suitable, then this
means that some TeX programming is needed to extend datetime2, and this
is out of scope of this manual, and we could give some pointer at some
TeX manuals (maybe a node should be dedicated to that, there is a very
good one here
I am not sure it was yet translated to English or German… ).

As for the scope of declarations, I think that this is not a matter of
contrasting LaTeX to TeX. Anyway, if you were considering LaTeX as a
stand-alone language processed by a compiler independant from TeX —
e.g. HeVeA or Tralics — then you would anyway have to document what sort
of scope the counter/command/length definitions have.


Le 04/06/2018 à 01:38, Hefferon, Jim S. a écrit :
> For me, I'm not so sure about getting far into any differences with TeX, just because of my idea of a reference manual, not because those difference are easy or well-known.
> I have a mental model of a high beginner  or intermediate user who is confused on some point (say, the difference between \\ and \newline inside a tabular) and there a refman would be a help.  Obviously, sometimes it is necessary to point to some explanation but at least in my head, the main goal is doing each item, rather than some global coverage.
> So on each item I'm trying to (a) include syntax, which we call Synopsis (and where latex-info tries to use square brackets both as a character and as a metacharacter, so I have been changing those) (b) give a one-sentence description (c) give a description (I don't like foobar so I try to find a model of something that would make a reader think "Yea, that's like what I want to do"), (d) cover any often-mistaken cases, which is why I search texhax, comp.text.tex, and StackExchange to see if there are trends.
> BTW, I really like your example of passing something to LaTeX on the command line.  Will Robertson wrote a great SE post about that, and I'd incorporate your example in it.
> Jim
> ________________________________________
> From: latexrefman <latexrefman-bounces at tug.org> on behalf of Vincent Belaïche <vincent.belaiche at gmail.com>
> Sent: Saturday, June 2, 2018 13:21
> To: latexrefman at tug.org
> Subject: Re: [latexrefman] latex-info Lengths
> Hello,
> Concerning lengths…
> I think we should be more clear about scope of defining length / counter
> / macros, and compare LaTeX to TeX, and how LaTeX adds on top of TeX.
> For instance LaTeX counters are defined globally contrary to TeX counters.
> LaTeX length and macros are to that respect (ie as far as scope is
> concerned) the same as TeX lengths and macros AFAIK, just the LaTeX
> interface makes more consistency checking, and as for lengths I  am not
> sure about the allocator (that defines some control sequence \somelength
> as \dimen<xxx>) is the same between TeX and LaTeX.
> Also, the info node about predefined counters \day, \month, etc… is
> confusing because these are TeX counter, not LaTeX counters, but the
> manual does not speak ever of TeX counters. This node should explain
> that one can fix the today date from the command line as follows:
> pdflatex \day2\month6\year2018 \input mydocument
> As far as dates are concerned, mentioning datetime2 rather than datetime
> is probably more « à la page » (meaning « up to date », but I wanted to
> teach you the French phrase for this…).
> As far as length units are concerned, it might be good to say that the
> difference of pt and bp, is that pt makes unit conversion easier — but I
> can't remember why ;-/ …
>     Vincent.
> Le 31/05/2018 à 18:48, Hefferon, Jim S. a écrit :
>> The next section.
>> Adjusted the definitions in Lengths, adding examples and error messages.  Because of \newlength also did the current doc's Definitions.  There, also adjusted the synopses for \newcommand.
>> I'll also note that I looked it up https://en.wikipedia.org/wiki/Radius, and it does say "conventional."  :-)
>> Jim
>> -----------
>> [N]ow, as throughout history, financial capacity and political perspicacity are inversely correlated. Long run salvation by men of business has never been highly regarded if it means disturbance of orderly life and convenience in the present. So inaction will be advocated in the present even though it means deep trouble in the future. Here, at least equally with communism, lies the threat to capitalism. It is what causes men who know that things are going quite wrong to say that things are fundamentally sound.
>>     -- John Kenneth Galbraith in The Great Crash, 1929

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