Re: Page numbers in ms keeps

[John A.]

John A. <john@ankarstrom.se> wrote:
> Does anyone have a good solution for this problem?
>
> .KF
> [...]
> The current page number is \n(PN.
> .KE
>
> If the floating keep above is moved to another page, because it doesn't
> fit on the current one, then the PN (and %, for that matter) register
> holds the incorrect page.

I just came up with a solution, which works for the majority of cases.

To illustrate, I have a TAG macro, which stores the current page number 
in a named register, to which I can refer using a REF macro later in the 
document:

.de TAG
.nr TAG_\\$1 \\n(PN
..
.de REF
\\$3\\n[TAG_\\$1]\\$2
..

To use the TAG macro within an ms keep (or indeed any other diversion), 
I now use the following:

\!.TAG tagname

This postpones the processing of the line until the diversion is 
actually inserted (see 5.25 "Diversions" in the groff manual).

Subsequently, TAG is called when the keep is inserted on the next page, 
which means that the PN register is set correctly. Neat!

Best regards
John

P.S.

The caveat is that \! doesn't work very well if you want to insert the 
page number into the keep/diversion itself (like in the example in my 
original message). It comes out in the wrong size, left-aligned etc. It 
can be fixed manually, though:

\!.fi
\!.sp \\n(PDu
\!.ps \\n(PSu
\!.vs \\n(VSu
\!.ll \\n(LLu
\!.ad b
\!The current page number is \\n(PN.
\!.nf

Using \!.PP directly kind of works, but leaves some small garbage above 
the paragraph -- surely, something is going wrong. Maybe there's someone 
here who knows what?