我有点困惑为什么这两个 MWE 的结果会导致不同的输出。
示例 1（期望输出）
在此示例中，我使用长度设置 y 坐标值：
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\setlength{\parindent}{0pt}
\newlength{\mydepth}%
\begin{document}
A
\begin{tikzpicture}
\coordinate (top right) at (0,0);
\setlength\mydepth{\dimexpr2in+2cm\relax}
\coordinate (bottom left) at (4in,-\mydepth);
\draw (bottom left) -- (top right);
\node[draw] (A) at ($(top right)!0.5!(bottom left)$) {CONTENT};
\draw[blue,line width=2pt] (current bounding box.south east) rectangle (current bounding box.north west);
\end{tikzpicture}
\end{document}
示例 2（输出不理想）
在此示例中，我使用宏设置 y 坐标值：
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\setlength{\parindent}{0pt}
\begin{document}
A
\begin{tikzpicture}
\coordinate (top right) at (0,0);
\edef\mydepth{\dimexpr2in+2cm\relax}
\coordinate (bottom left) at (4in,-\mydepth);
\draw (bottom left) -- (top right);
\node[draw] (A) at ($(top right)!0.5!(bottom left)$) {CONTENT};
\draw[blue,line width=2pt] (current bounding box.south east) rectangle (current bounding box.north west);
\end{tikzpicture}
\end{document}
实际上，对于第二个示例，我不需要宏。最初，此问题出现在以下代码中：
\coordinate (bottom left) at (4in,\dimexpr2in+2cm\relax);
所以问题其实不是宏对比长度。这是计算坐标中长度的问题。
答案1
使用
\edef\mydepth{\dimexpr2in+2cm\relax}
我收到语法错误
! You can't use '\dimexpr' in restricted horizontal mode
并且没有输出。
和
\edef\mydepth{\the\dimexpr2in+2cm\relax}
我得到与以下相同的输出
\setlength\mydepth{\dimexpr2in+2cm\relax}
添加\listfiles到您的第二个示例中，我收到一个错误，然后列表显示如下。您可以将文件版本与您的设置进行比较：
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\setlength{\parindent}{0pt}
\listfiles
\begin{document}
A
\begin{tikzpicture}
\coordinate (top right) at (0,0);
\edef\mydepth{\dimexpr2in+2cm\relax}
\coordinate (bottom left) at (4in,-\mydepth);
\draw (bottom left) -- (top right);
\node[draw] (A) at ($(top right)!0.5!(bottom left)$) {CONTENT};
\draw[blue,line width=2pt] (current bounding box.south east) rectangle (current bounding box.north west);
\end{tikzpicture}
\end{document}
! You can't use `\dimexpr' in restricted horizontal mode.
<argument> \dimexpr
l.14 ...oordinate (bottom left) at (4in,-\mydepth)
;
?
! Undefined control sequence.
\pgfmath@dimen@ ...men@@ #1=0.0pt\relax \pgfmath@
l.14 ...oordinate (bottom left) at (4in,-\mydepth)
;
?
! Missing number, treated as zero.
<to be read again>
\def
l.14 ...oordinate (bottom left) at (4in,-\mydepth)
;
?
! Illegal unit of measure (pt inserted).
<to be read again>
\def
l.14 ...oordinate (bottom left) at (4in,-\mydepth)
;
?
Runaway argument?
\pgfmath@number {0}\expandafter \ifcat \pgfmath@token@next \relax \let \ETC.
! Paragraph ended before \pgfmath@dimen@@ was complete.
<to be read again>
\par
l.15
?
! Package pgf Error: No shape named bottom left is known.
See the pgf package documentation for explanation.
Type H <return> for immediate help.
...
l.16 \draw (bottom left)
-- (top right);
?
! Package pgf Error: No shape named bottom left is known.
See the pgf package documentation for explanation.
Type H <return> for immediate help.
...
l.16 \draw (bottom left) -- (top right)
;
?
! Package pgf Error: No shape named bottom left is known.
See the pgf package documentation for explanation.
Type H <return> for immediate help.
...
l.17 ...aw] (A) at ($(top right)!0.5!(bottom left)
$) {CONTENT};
?
! Extra }, or forgotten \endgroup.
\endpgfpicture ... \pgf@x }\endgroup \hss \egroup
\pgf@insertlayers \endgrou...
l.21 \end{tikzpicture}
?
! LaTeX Error: \begin{tikzpicture} on input line 11 ended by \end{document}.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.23 \end{document}
?
! Missing \endgroup inserted.
<inserted text>
\endgroup
l.23 \end{document}
?
! Missing } inserted.
<inserted text>
}
l.23 \end{document}
?
Overfull \hbox (62.53825pt too wide) detected at line 23
[][][][][]
[]
[1
{/usr/local/texlive/2013/texmf-var/fonts/map/pdftex/updmap/pdftex.map}]
(./tkl111.aux)
*File List*
article.cls 2007/10/19 v1.4h Standard LaTeX document class
size10.clo 2007/10/19 v1.4h Standard LaTeX file (size option)
tikz.sty 2010/10/13 v2.10 (rcs-revision 1.76)
pgf.sty 2008/01/15 v2.10 (rcs-revision 1.12)
pgfrcs.sty 2010/10/25 v2.10 (rcs-revision 1.24)
everyshi.sty 2001/05/15 v3.00 EveryShipout Package (MS)
pgfrcs.code.tex
pgfcore.sty 2010/04/11 v2.10 (rcs-revision 1.7)
graphicx.sty 1999/02/16 v1.0f Enhanced LaTeX Graphics (DPC,SPQR)
keyval.sty 1999/03/16 v1.13 key=value parser (DPC)
graphics.sty 2009/02/05 v1.0o Standard LaTeX Graphics (DPC,SPQR)
trig.sty 1999/03/16 v1.09 sin cos tan (DPC)
graphics.cfg 2010/04/23 v1.9 graphics configuration of TeX Live
pdftex.def 2011/05/27 v0.06d Graphics/color for pdfTeX
infwarerr.sty 2010/04/08 v1.3 Providing info/warning/error messages (HO)
ltxcmds.sty 2011/11/09 v1.22 LaTeX kernel commands for general use (HO)
pgfsys.sty 2010/06/30 v2.10 (rcs-revision 1.37)
pgfsys.code.tex
pgfsyssoftpath.code.tex 2008/07/18 (rcs-revision 1.7)
pgfsysprotocol.code.tex 2006/10/16 (rcs-revision 1.4)
xcolor.sty 2007/01/21 v2.11 LaTeX color extensions (UK)
color.cfg 2007/01/18 v1.5 color configuration of teTeX/TeXLive
pgfcore.code.tex
pgfcomp-version-0-65.sty 2007/07/03 v2.10 (rcs-revision 1.7)
pgfcomp-version-1-18.sty 2007/07/23 v2.10 (rcs-revision 1.1)
pgffor.sty 2010/03/23 v2.10 (rcs-revision 1.18)
pgfkeys.sty
pgfkeys.code.tex
pgffor.code.tex
tikz.code.tex
supp-pdf.mkii
pdftexcmds.sty 2011/11/29 v0.20 Utility functions of pdfTeX for LuaTeX (HO)
ifluatex.sty 2010/03/01 v1.3 Provides the ifluatex switch (HO)
ifpdf.sty 2011/01/30 v2.3 Provides the ifpdf switch (HO)
epstopdf-base.sty 2010/02/09 v2.5 Base part for package epstopdf
grfext.sty 2010/08/19 v1.1 Manage graphics extensions (HO)
kvdefinekeys.sty 2011/04/07 v1.3 Define keys (HO)
kvoptions.sty 2011/06/30 v3.11 Key value format for package options (HO)
kvsetkeys.sty 2012/04/25 v1.16 Key value parser (HO)
etexcmds.sty 2011/02/16 v1.5 Avoid name clashes with e-TeX commands (HO)
epstopdf-sys.cfg 2010/07/13 v1.3 Configuration of (r)epstopdf for TeX Live
***********
)
(\end occurred inside a group at level 2)
### semi simple group (level 2) entered at line 12 (\begingroup)
### semi simple group (level 1) entered at line 11 (\begingroup)
### bottom level
(\end occurred when \iffalse on line 14 was incomplete)
(\end occurred when \ifx on line 14 was incomplete)
(\end occurred when \ifcat on line 14 was incomplete)
(\end occurred when \ifx on line 14 was incomplete)
(\end occurred when \iftrue on line 14 was incomplete)
(\end occurred when \iffalse on line 14 was incomplete)
Here is how much of TeX's memory you used:
答案2
%“icky” 输出是由于解析器代码缺失而插入空格的结果pgfmath。这可以从以下代码中看到：
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\newlength{\mydepth}%
\begin{document}
\hbox{\setlength\mydepth{\dimexpr0.2in+0.2cm}:\pgfmathparse{\mydepth}: \pgfmathresult,}
\hbox{\edef\mydepth{\dimexpr0.2in+0.2cm}:\pgfmathparse{\mydepth}: \pgfmathresult}
\end{document}
其结果为：
:: 20.14423,
: : 20.14423
有问题的命令是，在开头\pgfmath@parse@dimexpr@缺少：%{
\def\pgfmath@parse@dimexpr@{
\edef\pgfmathresult{\pgfmath@tonumber{\pgfmath@dimen}}%
\expandafter\pgfmath@stack@push@operand\expandafter{\pgfmathresult}%
\pgfmath@parse@@operator%
}
通过添加，%空间消失了：
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\newlength{\mydepth}%
\makeatletter
\def\pgfmath@parse@dimexpr@{%
\edef\pgfmathresult{\pgfmath@tonumber{\pgfmath@dimen}}%
\expandafter\pgfmath@stack@push@operand\expandafter{\pgfmathresult}%
\pgfmath@parse@@operator%
}
\makeatother
\begin{document}
\hbox{\setlength\mydepth{\dimexpr0.2in+0.2cm}:\pgfmathparse{\mydepth}: \pgfmathresult,}
\hbox{\edef\mydepth{\dimexpr0.2in+0.2cm}:\pgfmathparse{\mydepth}: \pgfmathresult}
\end{document}
其结果为：
:: 20.14423,
:: 20.14423
这是一个错误，PGFmath但现在已在 PGF CVS 版本中修复。