為了學習，我嘗試使用（並理解）LuaTeX 代碼作為邊注這裡在 LuaLaTeX 中。
因此我做了這個最小的設定：
\documentclass{article}
\usepackage{luatexbase}
\directlua{
local HLIST = node.id("hlist")
local RULE = node.id("rule")
local GLUE = node.id("glue")
local KERN = node.id("kern")
local WHAT = node.id("whatsit")
local COL = node.subtype("pdf_colorstack")
mark_lines = function (head)
for mark in node.traverse_id(WHAT, head) do
local attr = node.has_attribute(mark, 100)
if attr then
local item = mark.next
while item do
if item.id == HLIST then
node.set_attribute(item, 100, attr)
item = nil
else
item = item.next
end
end
head = node.remove(head, mark)
end
end
return head
end
process_marginalia = function (head)
local remainingheight, first, item = 0, true, node.slide(head)
while item do
if node.has_field(item, "kern") then
if not first then
remainingheight = remainingheight + item.kern
end
elseif node.has_field(item, "spec") then
if not first then
remainingheight = remainingheight + item.spec.width
end
elseif node.has_field(item, "height") then
if first then
first = false
else
remainingheight = remainingheight + item.depth
end
local attr = node.has_attribute(item, 100)
if attr then
local note = node.copy(tex.box[attr])
local upward = note.depth - node.tail(note.list).depth
if upward > remainingheight then
upward = remainingheight - upward
else
upward = 0
end
local kern = node.new(KERN, 1)
kern.kern = upward - note.height - item.depth
node.insert_before(note.list, note.list, kern)
note.list = kern
note.height, note.depth = 0, 0
node.insert_after(head, item, note)
note.shift = tex.hsize + tex.sp("1em")
first = true
remainingheight = upward
else
remainingheight = remainingheight + item.height
end
end
item = item.prev
end
end
luatexbase.add_to_callback("post_linebreak_filter", mark_lines, "mark_lines")
}
\newcount\notecount
\def\note#1{%
\advance\notecount 1%
\expandafter\newbox\csname marginnote_\the\notecount\endcsname%
\expandafter\setbox\csname marginnote_\the\notecount\endcsname=\vtop{\hsize=4cm\rightskip=0pt plus 1fil\noindent\it #1}%
\bgroup\attribute100=\expandafter\the\csname marginnote_\the\notecount\endcsname\vadjust pre {\pdfliteral{}}\egroup%
}
\begin{document}
Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.\note{Please do not fill this with too much text}
\output{\directlua{process_marginalia(tex.box[255].list)}\shipout\box255}
\end{document}
但是 LuaLaTeX 總是在該行拋出錯誤\setbox（LuaTeX 在修改版本中也是如此）：
! Missing number, treated as zero.
<to be read again>
\marginnote_1
l.85 ...{Please do not fill this with too much text}
?
我不完全理解為什麼會出現這種情況以及如何解決它。所以我的問題是：為什麼 TeX 不喜歡這樣\setbox？
答案1
這是一種明顯的“空間缺失綜合症”
\def\note#1{%
\advance\notecount 1
\expandafter\newbox\csname marginnote_\the\notecount\endcsname%
\expandafter\setbox\csname marginnote_\the\notecount\endcsname=\vtop{\hsize=4cm\rightskip=0pt plus 1fil\noindent\it #1}%
\bgroup\attribute100=\expandafter\the\csname marginnote_\the\notecount\endcsname\vadjust pre {\pdfliteral{}}\egroup%
}
你有一個%之後1。
另外你還需要\usepackage{luatex85}。經過這些修復後，我得到了
發生了什麼事？常數後面缺少的空格1會觸發下一個標記的擴展，即\expandafter，這又會觸發\csname，因此以前的\notecount使用的值。
你會得到“丟失的數字”，因為框寄存器實際上是整數；您的巨集分配了\marginnote_0，\setbox而是看到了\marginnote_1.