On 2/24/24 14:30, Wolfgang Schuster wrote:

Michael Guravage schrieb am 23.02.2024 um 10:07:

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Greetings,

I would like to use the nextquadruple and beforequadruple pagebreakhandlers described at the bottom of the wiki's imposition page. However, the examples complain of an error invoking the \installpagebreakhandler command.

The wiki page was last updated nearly four years ago. Is anyone using updated versions of these?

You can use quadruple out of the box.

Hi Wolfgang, I’m also interested a solution for this. I’m afraid I cannot make your sample work: \setuppapersize[A5][A4, landscape] \setuparranging[2UP] \setuppagenumbering[alternative={singlesided,doublesided}] \starttext \samplefile{lorem} \page[quadruple] page before the quadruple (must be 3, not 4) \page[yes, quadruple] page before the quadruple (must be 7, not 8) \stoptext I haven’t tested what "\setuppagenumbering[alternative={singlesided,doublesided}]" would cause in my documents. In any case, I get real quadruple, not before the quadruple. What am I missing here? Many thanks for your help, Pablo

On 2/28/24 11:56, Bruce Horrocks wrote:

[...] The sample works for me if you set plain A4 and doublesided, thus:

\setuppagenumbering[alternative={doublesided}] \starttext \samplefile{lorem} \page[quadruple] page before the quadruple (must be 3, not 4) \page[yes, quadruple] page before the quadruple (must be 7, not 8) \stoptext

This puts the "page before quadruple" text on page 4 which is the last side of the first four sides, if that makes sense.

Many thanks for your reply, Bruce. \page[quadruple] works fine putting content on realpage numbers that can be divided by 4 (with modulo 0). As far as I get, Michael was looking to place content on realpage numbers get modulo 3 when divided by 4. At least, this is what would fit my needs to place the imprint on the (excuse the Latin adjective [before the last]) penultima page of a booklet. This is why beforequadruple would make sense. I guess some Lua magic could do that, computing x to the follwing page that "x % 4 = 3" (and then \page[x]). I will try to find a trick for that, but not now. Many thanks for your help, Pablo

Pablo Rodriguez via ntg-context schrieb am 28.02.2024 um 19:02:

On 2/28/24 12:24, Pablo Rodriguez via ntg-context wrote:

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[...] This is why beforequadruple would make sense. I guess some Lua magic could do that, computing x to the follwing page that "x % 4 = 3" (and then \page[x]).

I will try to find a trick for that, but not now.

Replying to myself, this is a command to compute next numbers before and after quadruples (with application to \realpageno):

\starttext \def\beforequadruplenumber#1% {\ifnum\modulonumber{4}{#1} = 1 \the\numexpr #1 + 2 \orelse\ifnum\modulonumber{4}{#1} = 2 \the\numexpr #1 + 1 \orelse\ifnum\modulonumber{4}{#1} = 3 \the\numexpr #1 + 4 \else \the\numexpr #1 + 3 \fi}

\def\beforequadruplenumber#1% {\ifcase\numexpr#1+1;4\relax \number\numexpr#1+4\relax \else \number\numexpr#1+3-#1;4\relax \fi}

\def\afterquadruplenumber#1% {\ifnum\modulonumber{4}{#1} = 1 \the\numexpr #1 + 4 \orelse\ifnum\modulonumber{4}{#1} = 2 \the\numexpr #1 + 3 \orelse\ifnum\modulonumber{4}{#1} = 3 \the\numexpr #1 + 2 \else \the\numexpr #1 +1 \fi}

\def\afterquadruplenumber#1% {\ifcase\numexpr#1;4\relax \number\numexpr#1+1\relax \else \number\numexpr#1+5-#1;4\relax \fi} Wolfgang

Pablo Rodriguez via ntg-context schrieb am 04.03.2024 um 20:00:

On 2/28/24 19:28, Wolfgang Schuster wrote:

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[...] \def\beforequadruplenumber#1% {\ifcase\numexpr#1+1;4\relax \number\numexpr#1+4\relax \else \number\numexpr#1+3-#1;4\relax \fi}

Sorry for not having answered before, Wolfgang.

I’m afraid I don’t get how \ifcase is deployed with as conditional (being \ifcase used to give numbers for weekdays or months).

The \ifcase command is the TeX version of a switch statement from other programming languages. The first case in \ifcase checks against zero which is shorter than writing "\ifnum ... = 0".

The semicolon is also mysterious to me, I don’t know what it does there in plain language.

The semicolon is a undocumented extension (I noticed it in the definition of \page[quadruple]) of \numexpr in Luametatex for the modulus operator.

Sorry, I know it has to be simple, but the syntax is too cryptic for me.

Could you write the first line in plain language?

Look at the second example of the Lua code in the example below for each command (the first example is your version), the third example is just a condensed version of example 2.

Sorry for asking that. I’m afraid this would be the only way I could get what \ifcase is doing there.

As was mentioned above I used it as a check when the remainder was 0. %%%% begin example \startluacode --~ interfaces.implement { --~ name = "beforequadruplenumber", --~ arguments = "integer", --~ actions = function(n) --~ if n % 4 == 0 then --~ context(n + 3) --~ elseif n % 4 == 1 then --~ context(n + 2) --~ elseif n % 4 == 2 then --~ context(n + 1) --~ elseif n % 4 == 3 then --~ context(n + 4) --~ end --~ end --~ } --~ interfaces.implement { --~ name = "beforequadruplenumber", --~ arguments = "integer", --~ actions = function(n) --~ if (n + 1) % 4 == 0 then --~ context(n + 4) --~ else --~ context(n + 3 - n % 4) --~ end --~ end --~ } interfaces.implement { name = "beforequadruplenumber", arguments = "integer", actions = function(n) context(n + (((n + 1) % 4 == 0) and 4 or (3 - n % 4))) end } --~ interfaces.implement { --~ name = "afterquadruplenumber", --~ arguments = "integer", --~ actions = function(n) --~ if n % 4 == 0 then --~ context(n + 1) --~ elseif n % 4 == 1 then --~ context(n + 4) --~ elseif n % 4 == 2 then --~ context(n + 3) --~ elseif n % 4 == 3 then --~ context(n + 2) --~ end --~ end --~ } --~ interfaces.implement { --~ name = "afterquadruplenumber", --~ arguments = "integer", --~ actions = function(n) --~ if n % 4 == 0 then --~ context(n + 1) --~ else --~ context(n + 5 - n % 4) --~ end --~ end --~ } interfaces.implement { name = "afterquadruplenumber", arguments = "integer", actions = function(n) context(n + ((n % 4 == 0) and 1 or (5 - n % 4))) end } \stopluacode \unprotect \def\beforequadruplenumber#1{\clf_beforequadruplenumber\numexpr#1\relax} \def\afterquadruplenumber #1{\clf_afterquadruplenumber \numexpr#1\relax} \protect \starttext \dorecurse{20}{\recurselevel\space = \beforequadruplenumber{\recurselevel}\par}\page \dorecurse{20}{\recurselevel\space = \afterquadruplenumber {\recurselevel}\par} \stoptext %%%% end example Wolfgang

Pablo Rodriguez via ntg-context schrieb am 06.03.2024 um 20:17:

On 3/6/24 19:50, Wolfgang Schuster wrote:

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[...] Could you write the first line in plain language?

Look at the second example of the Lua code in the example below for each command (the first example is your version), the third example is just a condensed version of example 2.

Many thanks for your extended explanation, Wolfgang.

Here is another solution which uses \ifcase the select a different case dependent on the value of the remainder. \def\beforequadruplenumber#1% {\ifcase\numexpr#1;4\relax \the\numexpr#1+3\relax % remainder = 0 \or \the\numexpr#1+2\relax % remainder = 1 \or \the\numexpr#1+1\relax % remainder = 2 \or \the\numexpr#1+4\relax % remainder = 3 \fi} \def\afterquadruplenumber#1% {\ifcase\numexpr#1;4\relax \the\numexpr#1+1\relax % remainder = 0 \or \the\numexpr#1+4\relax % remainder = 1 \or \the\numexpr#1+3\relax % remainder = 2 \or \the\numexpr#1+2\relax % remainder = 3 \fi}

Now it is clearer to me (although I need some time to learn from it).

When you use \numexpr to perform arithmetic in TeX it is recommended to add a final \relax to stop the command from scanning to additional values, e.g. in the example below \testone takes value beyond the argument because \numexpr hasn't ended yet. \starttext \def\testone#1{\the\numexpr #1 + 1 } \testone{1} + 1 \def\testtwo#1{\the\numexpr #1 + 1 \relax} \testtwo{1} + 1 \stoptext Wolfgang

Hans Hagen schrieb am 06.03.2024 um 21:38:

On 3/6/2024 7:50 PM, Wolfgang Schuster wrote:

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The semicolon is a undocumented extension (I noticed it in the definition of \page[quadruple]) of \numexpr in Luametatex for the modulus operator.

One of these days I have to write the pending section in th elow level manual and also explain this:

\starttext     \ifnum  10  = 11 wrong \else okay  \fi     \ifnum  10 != 11 okay  \else wrong \fi     \ifnum  10 !> 11 okay  \else wrong \fi     \ifnum  10 !< 11 wrong \else okay  \fi     \ifnum  10 ≤  11 okay  \else wrong \fi     \ifnum  10 ≥  11 wrong \else okay  \fi     \ifnum  10 ≰  11 okay  \else wrong \fi     \ifnum  10 ≱  11 wrong \else okay  \fi     \ifnum "F0 ∈ "F0 okay  \else wrong \fi     \ifnum "F0 ∉ "F0 wrong \else okay  \fi \stoptext

These new features are mentioned in the Luametatex manual but not the additions to \numexpr (I checked and : is mentioned but ; is missing). \starttext \startlines \number\numexpr 5 + 2 \relax \number\numexpr 5 - 2 \relax \number\numexpr 5 * 2 \relax \number\numexpr 5 / 2 \relax \number\numexpr 5 : 2 \relax % new! \number\numexpr 5 ; 2 \relax % new! \stoplines \stoptext Wolfgang