From d5c03c9d88143bb1fd803f25198b48f42ab9d9a7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Tue, 22 Jun 2021 15:00:53 +0200
Subject: Remove all configuration registers (mt, mb, tt, tb)

---
 example.pdf | Bin 82588 -> 84913 bytes
 example.t   | 155 +++++++++++++++++++++++++++++++++++++++---------------------
 g.tmac      | 125 ++++++++++++++++++++++++++----------------------
 3 files changed, 170 insertions(+), 110 deletions(-)

diff --git a/example.pdf b/example.pdf
index b69f26b..c0146d3 100644
Binary files a/example.pdf and b/example.pdf differ
diff --git a/example.t b/example.t
index 2fc9bd1..87f6bd0 100644
--- a/example.t
+++ b/example.t
@@ -1,5 +1,16 @@
 .so g.tmac
 .
+.de @h
+. sp |36p
+. tl ''-%-''
+. sp |1i
+..
+.
+.de @f
+. sp |\\n(.pu-48p
+. tl ''\\*(%e''
+.. 
+.
 . \" configure environments
 .@e p
 . nr sq \n(sp
@@ -160,42 +171,6 @@ and do not support these registers.
 .
 .
 .h
-Global settings
-.p
-Thanks to the reliance on environments,
-there are only four global string values
-controlling the state of
-.i mg :
-.n 1
-.c mt ,
-the margin at the top of the page
-.n
-.c mb ,
-the margin at the bottom of the page
-.n
-.c tt ,
-the text in the top margin
-.n
-.c tb ,
-the text in the bottom margin
-.p
-The
-.c tt
-and
-.c tb
-registers are passed to troff's
-.c tl
-request and should be formatted accordingly.
-By default,
-.c tt
-is empty and
-.c tb
-is set to
-.c ''%'' ,
-displaying the page number in the center.
-.
-.
-.h
 External macros
 .p
 .i Mg
@@ -298,6 +273,14 @@ international date, like
 .c e :
 English date, like
 .q "21 June 2021"
+.p
+The date formats are defined in strings prefixed with a percent sign
+.c % ): (
+.c %i
+and
+.c %e
+are provided by default,
+but more may be added by the user.
 .
 .s
 Other macros
@@ -337,6 +320,7 @@ For example, the following code
 \&.q
 This is a quotation\\c
 \&.(
+.ne 1
 This is a footnote.
 \&.) .
 .p
@@ -347,12 +331,14 @@ This is a quotation\c
 This is a footnote.
 .) .
 .p
-.i Mg
-does not account for cases where a footnote, because of its height,
-pushes the place where it is referenced to the next page.
-In such cases, the reference will simply appear on the page
-following the footnote.
-When this happens, the user must account for it manually.
+If
+.c (
+and
+.c )
+are called at such a position that the collected footnotes
+cannot fit on the current page,
+.i mg
+will print the footnotes on the next page instead.
 .p
 The
 .c q
@@ -398,14 +384,59 @@ Internal macros
 .i Mg 's
 internal macros are generally not meant to be used outside of
 .i g.tmac .
+Documented in this section are the exceptions to this rule.
+For examples of how these macros are used in practice,
+see the FAQ section below.
+.
+.s
+Margin macros
+.p
+The
+.c @h ,
+.c @f ,
+.c @th
+and
+.c @tf
+macros control the page header and footer.
+.p
+At document initialization,
+.i mg
+automatically creates traps for
+.c @th
+and
+.c @tf .
+When sprung,
+.c @th
+and
+.c @tf
+call
+.c @h
+and
+.c @t ,
+which control the text and spacing of the header and footer.
+.p
+.i Mg
+will avoid creating a trap for
+.c @tf
+if any trap has already been set before document initialization.
+This means that users can override the position of the
+.c @tf
+trap by setting it themselves.
+Likewise, users can redefine
+.c @h
+and
+.c @f
+to change the content of the header and footer.
+.
+.s
+Environment macros
+.p
 The environment-related macros
 .c (e ,
 .c @e
 and
 .c @c
-are, however, excepted from this rule,
-as it may be desirable to define custom environments
-for advanced documents.
+may be used in advanced documents to define custom environments.
 .p
 At the present,
 .c (e
@@ -428,14 +459,6 @@ special environment variables
 (see
 .i Environments
 above).
-.p
-For examples of how
-.c (e ,
-.c @e
-and
-.c @c
-are used in practice,
-see the FAQ section below.
 .
 .
 .h
@@ -509,6 +532,32 @@ How do I customize the default appearance of footnotes?
 \&.ps +1p
 .
 .s
+How do I redefine the page header?
+.l
+\&.de @h
+\&. \\" set position of header text
+\&. sp |36p
+\&. \\" set header text
+\&. tl 'left'center'right'
+\&. \\" set position of page text
+\&. sp |1i
+\&..
+.
+.s
+How do I redefine the page footer?
+.l
+\&.\\" set position of footer trap
+\&.\\" (must be done before any macros have been called)
+\&.wh -1i @tf
+\&.
+\&.de @f
+\&. \\" set position of footer text
+\&. \\" (must be below the footer trap)
+\&. sp |\\\\n(.pu-48p
+\&. tl 'left'center'right'
+\&..
+.
+.s
 How do I prevent a section from being broken up by a page break?
 .p
 Some macro packages have a concept of
diff --git a/g.tmac b/g.tmac
index 8475988..48ecc6e 100644
--- a/g.tmac
+++ b/g.tmac
@@ -12,16 +12,16 @@
 .\" When editing the source of mg, keep the  "/.
 .\" following rules in mind:                 "/.
 .\"                                          "/.
-.\" * Prefix temporary registers with _.     "/.
-.\" * Prefix temporary strings with _.       "/.
-.\" * Prefix internal environments with @.   "/.
-.\" * Prefix internal registers with @.      "/.
+.\" * Prefix temporary strings and registers "/.
+.\"   with _.                                "/.
+.\" * Prefix internal registers and environ- "/.
+.\"   ments with @.                          "/.
 .\" * Prefix internal macros with @ (normal  "/.
-.\" macros), * (variants of the same macro)  "/.
-.\" or % (strings).                          "/.
+.\"   macros), * (variants of the same       "/.
+.\"   macro) or % (strings).                 "/.
 .\" * Place macros in alphabetical order.    "/.
-.\" * Do not use .ev and .evc outside of     "/.
-.\" wrapper macros like (e, @e and @c.       "/.
+.\" * Do not use .ev and .evc directly; use  "/.
+.\"   (e, @e and @c instead.                 "/.
 .\"                                          "/.
 .
 .eo \" disable backslash escapes
@@ -31,15 +31,9 @@
 .\" @a -- setup document
 .de @a
 .
-. \" configure initial options
-. @nr mt 1i \" top margin
-. @nr mb 1i \" bottom margin
-. @ds tt '''' \" text in top margin
-. @ds tb ''%'' \" text in bottom margin
-.
 . \" initialize document
 . wh 0 @th
-. wh -\n(mbu @tf
+. if \n(.t=\n(.p .wh -1i @tf
 . sp 1u \" trigger header
 .
 . \" configure environments
@@ -96,6 +90,30 @@
 . (e @m \" margins (header, footer)
 .  @c 0
 . (e
+.
+. \" set date formats
+. af mo 00
+. af dy 00
+. ds %i \n[year]-\n(mo-\n(dy
+. af mo 1
+. af dy 1
+. ds %e \n(dy
+. ie \n(mo=1 .ds %e \*(%e January
+. el .ie \n(mo=2 .ds %e \*(%e February
+. el .ie \n(mo=3 .ds %e \*(%e March
+. el .ie \n(mo=4 .ds %e \*(%e April
+. el .ie \n(mo=5 .ds %e \*(%e May
+. el .ie \n(mo=6 .ds %e \*(%e June
+. el .ie \n(mo=7 .ds %e \*(%e July
+. el .ie \n(mo=8 .ds %e \*(%e August
+. el .ie \n(mo=9 .ds %e \*(%e September
+. el .ie \n(mo=10 .ds %e \*(%e October
+. el .ie \n(mo=11 .ds %e \*(%e November
+. el .ds %e \*(%e December
+. ds %e \*(%e \n[year]
+..
+.
+.
 ..
 .
 . \" @c -- copy environment
@@ -161,6 +179,21 @@
 . \}
 ..
 .
+.\" @f -- footer
+.de @f
+. sp |\n(.pu-48p
+. tl ''%''
+..
+.
+.\" @h -- header
+.de @h
+. sp |36p
+. tl ''''
+. sp |1i
+..
+.
+..
+.
 .\" @nr -- set default numeric value
 .de @nr
 . if \n[\$1]=0 .nr \$1 \$2
@@ -169,11 +202,15 @@
 .\" @tf -- footer trap
 .de @tf
 .
+. \" skip automatic trigger if manual mode active, unless forced
+. if \n(@m>0 .if !'\$1'f' \{\
+.  nr @m -1
+.  return
+. \}
+.
 . \" print footer
 . (e @m
-. rt \n(.pu-\n(mbu \" return to correct position if pushed down
-. sp \n(mbu-2v-24p
-. tl \*(tb
+. @f
 ' bp
 ..
 .
@@ -181,10 +218,7 @@
 .de @th
 . (e @m
 . rt 0
-. sp 24p
-. tl \*(tt
-. rt 0
-. sp \n(mtu
+. @h
 . (e \*[%env]
 . ns
 ..
@@ -192,9 +226,7 @@
 .\" @tn -- footnote trap
 .de @tn
 .
-. \" override footer
-. ch @tf
-.
+. nr @m 1
 . \" print collected footnotes
 . (e @m
 ___________________
@@ -206,12 +238,10 @@ ___________________
 .
 . \" clear footnotes
 . ch @tn
+. nr @.t 0
 . nr @dn 0
 . rm @n
-.
-. \" trigger and restore footer
-. @tf
-. wh -\n(mbu @tf
+. @tf f
 ..
 .
 .
@@ -283,34 +313,9 @@ ___________________
 .de d
 . br
 . @e d
-.
-. \" international format
-. ie '\$1'i' \{\
-.  af mo 00
-.  af dy 00
-\n[year]-\n(mo-\n(dy
-.  af mo 1
-.  af dy 1
-. \}
-.
-. \" english format
-. el .if '\$1'e' \{\
-\n(dy
-. ie \n(mo=1 January
-. el .ie \n(mo=2 February
-. el .ie \n(mo=3 March
-. el .ie \n(mo=4 April
-. el .ie \n(mo=5 May
-. el .ie \n(mo=6 June
-. el .ie \n(mo=7 July
-. el .ie \n(mo=8 August
-. el .ie \n(mo=9 September
-. el .ie \n(mo=10 October
-. el .ie \n(mo=11 November
-. el December
-\n[year]
-. \}
+. if !'\$1'' \*(%\$1
 ..
+.
 .\" h -- heading
 .de h
 . br
@@ -321,6 +326,7 @@ ___________________
 .\" l -- literal display
 .de l
 . br
+. w ll
 . @e l
 ..
 .
@@ -371,10 +377,15 @@ ___________________
 . ie !'\$1'' \&\$1
 . el \&
 .
+. \" get position of footer (or next trap)
+. if \n[@.t]=0 .nr @.t \n(nl+\n(.t
+.
+.
 . \" print footnote at bottom of page
 . ch @tn
 . nr @dn +\n(dnu
-. if !'\n(dn'0' .wh -\n[@dn]u-\n(mbu-12p @tn
+. nr _tn \n[@.t]u-\n[@dn]u-12p
+. wh \n[_tn]u @tn
 ..
 .
 .\" w -- want space
-- 
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