Re: Comprehension problem with macros

[Oliver Corff]

Hi Ralph,

yes, I remember having heard of the two different modes but had only a
passive understanding.

Thank you for pointing this out!

I also see that you avoid going through .ie n < 10 then n .el \*[n]
construction. I was not quite sure if I could abuse single-digit numbers
in such a way.

Best regards,

Oliver.


On 23/04/2023 14:24, Ralph Corderoy wrote:
> Hi Oliver,
>
> > .nr number 0 1
> > .while (\n[number] < 16) \{\
> > .ie (\n[number] < 10) \[u4E0\n[number]]
> > .el \[u4E0\*[\n[number]]]
> > .nr number +1
> > .\}
> >
> > So far, everything works perfectly.
> >
> > However, if I wrap this loop in a macro like
> >
> > .de myline
> > .\" material as above
> > ..
> The text after .de is read twice.  Once when the macro is defined and
> again when it is executed.  The reading occurs in two different modes.
> See section 7 of CSTR 54.  https://troff.org/54.pdf
>
> For example, \nn puts the value of number-register n when the macro is
> defined into the macro whereas \\nn delays getting the value of n to
> when the macro is executed.
>
> Here's a variation on your test.
>
>      $ cat oliver.tr
>      .pl 2
>      .
>      .ds 0 0
>      .ds 1 1
>      .ds 2 2
>      .ds 3 3
>      .ds 4 4
>      .ds 5 5
>      .ds 6 6
>      .ds 7 7
>      .ds 8 8
>      .ds 9 9
>      .ds 10 A
>      .ds 11 B
>      .ds 12 C
>      .ds 13 D
>      .ds 14 E
>      .ds 15 F
>      .
>      .nr n 0 1
>      .while (\n[n] < 16) \{\
>      \[u216\*[\nn]]
>      .nr n +1
>      .\}
>      .br
>      .
>      .de m
>      .nr n 0 1
>      .while (\\n[n] < 16) \\{\\
>      \\[u216\\*[\\nn]]
>      .nr n +1
>      .\\}
>      ..
>      .m
>      $ troff -Tutf8 oliver.tr | grotty
>      Ⅰ Ⅱ Ⅲ Ⅳ Ⅴ Ⅵ Ⅶ Ⅷ Ⅸ Ⅹ Ⅺ Ⅻ Ⅼ Ⅽ Ⅾ Ⅿ
>      Ⅰ Ⅱ Ⅲ Ⅳ Ⅴ Ⅵ Ⅶ Ⅷ Ⅸ Ⅹ Ⅺ Ⅻ Ⅼ Ⅽ Ⅾ Ⅿ
>      $
--
Dr. Oliver Corff
Wittelsbacherstr. 5A
10707 Berlin
G E R M A N Y
Tel.: +49-30-85727260
Mail: oliver.corff@email.de