mystyle/.style= {...}也许被使用？
我想知道如何验证样式是否真正定义，在这种情况下，我想知道样式是否为空？
是否可以使用\pgfkeysifdefined来获取第一个结果？
答案1
\documentclass{standalone}
\usepackage{tikz}
\makeatletter
\def\pgfkeysifstyledefined#1#2#3{%
\pgfkeys@ifcsname pgfk@#1/.@cmd\endcsname#2\else#3\fi}
\def\pgfkeysifstyleempty#1{%
\expandafter\expandafter\expandafter\pgfkeysifstyleempty@i
\csname pgfk@#1/.@cmd\endcsname\pgfeov}
\def\pgfkeysifstyleempty@i\pgfkeysalso#1#2#3{%
\if\relax\detokenize{#1}\relax
#2%
\else
#3%
\fi}
\makeatother
\begin{document}
\pgfkeysifstyledefined{/tikz/my style}{Defined}{Undefined}
\tikzset{my style/.style = {}}
\pgfkeysifstyledefined{/tikz/my style}{Defined}{Undefined}
\pgfkeysifstyleempty{/tikz/my style}{Empty}{Non empty}
\tikzset{my style/.style = {Test}}
\pgfkeysifstyleempty{/tikz/my style}{Empty}{Non empty}
\end{document}
答案2
看起来不是——.style是一个设置 的处理程序.code，而后者又是一个设置内部.@cmd属性的处理程序。使用 Ryan Reich 的非常酷的trace-pgfkeys包（来自这个问题），以下代码
\documentclass{article}
\usepackage{pgfkeys}
\usepackage[tracemacros]{trace-pgfkeys}
\pgfkeystracelevel{verbose}
\begin{document}
\makeatletter
\typeout{Setting /test1/.style}
\pgfkeys{/test1/.style={shape=rectangle}}
\typeout{Checking ifdefine /test1/.style}
\pgfkeysifdefined{/test1/.style}{True}{False}
\typeout{Checking ifdefine /test1/.code}
\pgfkeysifdefined{/test1/.code}{True}{False}
\typeout{Checking ifdefine /test1/.@cmd}
\pgfkeysifdefined{/test1/.@cmd}{True}{False}
\typeout{Checking ifdefine /test-missing/.style}
\pgfkeysifdefined{/test-missing/.style}{True}{False}
\typeout{Checking ifdefine /test-missing/.code}
\pgfkeysifdefined{/test-missing/.code}{True}{False}
\typeout{Checking ifdefine /test-missing/.@cmd}
\pgfkeysifdefined{/test-missing/.@cmd}{True}{False}
\typeout{Setting /test2/.style to nothing}
\pgfkeys{/test2/.style=}
\pgfkeysgetvalue{/test2/.@cmd}{\test}
\ifx\test\relax Empty \else Not empty \fi
\end{document}
生成以下文件：
False False True
False False False
Not empty
以及大量有用的调试输出，以下是设置的跟踪/test1/.style：
Setting /test1/.style
[trace-pgfkeys]-: Tracing \pgfkeys call.
[trace-pgfkeys]-+ Key/value list: (/test1/.style={shape=rectangle})
[trace-pgfkeys]-+ Current key-value: (/test1/.style={shape=rectangle})
[trace-pgfkeys]-+ \pgfkeyscurrentkey (given): /test1/.style
[trace-pgfkeys]-: Full key; no path added.
[trace-pgfkeys]-> \pgfkeyscurrentkey : /test1/.style
[trace-pgfkeys]-+ \pgfkeyscurrentvalue : (shape=rectangle)
[trace-pgfkeys]-: Case one: key code?
[trace-pgfkeys]-: Case two: key value?
[trace-pgfkeys]-: Case three: key unknown. Splitting the path.
[trace-pgfkeys]-+ \pgfkeyscurrentpath (/test1)
[trace-pgfkeys]-+ \pgfkeyscurrentname (.style)
[trace-pgfkeys]-: Checking whether a handler is defined.
[trace-pgfkeys]-+ Executing all handlers.
[trace-pgfkeys]-: Tracing \pgfkeysgetvalue .
[trace-pgfkeys]-: Value: (\long macro:#1\pgfeov ->\pgfkeys {\pgfkeyscurrentpath /.code=\pgfkeysalso {#1}})
[trace-pgfkeys]--+ Storing key value in \pgfkeys@code
[trace-pgfkeys]--> Storing: /handlers/.style/.@cmd
[trace-pgfkeys]--+ Done storing.
[trace-pgfkeys]-: Handler code:
[trace-pgfkeys]-: \long macro:#1\pgfeov ->\pgfkeys {\pgfkeyscurrentpath /.code=\pgfkeysalso {#1}}
[trace-pgfkeys]--+ Executing handler.
[trace-pgfkeys]--> Handler: /handlers/.style
[trace-pgfkeys]---: Tracing \pgfkeys call.
[trace-pgfkeys]---+ Key/value list: (\pgfkeyscurrentpath /.code=\pgfkeysalso {shape=rectangle})
[trace-pgfkeys]---+ Current key-value: (\pgfkeyscurrentpath /.code=\pgfkeysalso {shape=rectangle})
[trace-pgfkeys]---+ \pgfkeyscurrentkey (given): /test1/.code
[trace-pgfkeys]---: Full key; no path added.
[trace-pgfkeys]---> \pgfkeyscurrentkey : /test1/.code
[trace-pgfkeys]---+ \pgfkeyscurrentvalue : (\pgfkeysalso {shape=rectangle})
[trace-pgfkeys]---: Case one: key code?
[trace-pgfkeys]---: Case two: key value?
[trace-pgfkeys]---: Case three: key unknown. Splitting the path.
[trace-pgfkeys]---+ \pgfkeyscurrentpath (/test1)
[trace-pgfkeys]---+ \pgfkeyscurrentname (.code)
[trace-pgfkeys]---: Checking whether a handler is defined.
[trace-pgfkeys]---+ Executing all handlers.
[trace-pgfkeys]---: Tracing \pgfkeysgetvalue .
[trace-pgfkeys]---: Value: (\long macro:#1\pgfeov ->\pgfkeysdef {\pgfkeyscurrentpath }{#1})
[trace-pgfkeys]----+ Storing key value in \pgfkeys@code
[trace-pgfkeys]----> Storing: /handlers/.code/.@cmd
[trace-pgfkeys]----+ Done storing.
[trace-pgfkeys]---: Handler code:
[trace-pgfkeys]---: \long macro:#1\pgfeov ->\pgfkeysdef {\pgfkeyscurrentpath }{#1}
[trace-pgfkeys]----+ Executing handler.
[trace-pgfkeys]----> Handler: /handlers/.code
[trace-pgfkeys]----: Tracing \pgfkeysdef .
[trace-pgfkeys]----: Code: (\pgfkeysalso {shape=rectangle})
[trace-pgfkeys]-----+ Defining key code.
[trace-pgfkeys]-----> New code: /test1
[trace-pgfkeys]-----: Tracing \pgfkeyslet .
[trace-pgfkeys]------+ Assigning key from \pgfkeys@temp
[trace-pgfkeys]------> Assigning: /test1/.@cmd
[trace-pgfkeys]------+ Done assigning.
[trace-pgfkeys]-----+ Done defining.
[trace-pgfkeys]----+ Done defining.
[trace-pgfkeys]---+ Execution finished.
[trace-pgfkeys]--+ Last key processed.
[trace-pgfkeys]-+ Execution finished.
[trace-pgfkeys]+ Last key processed.
请注意，/.style有一个/.@cmd，它反过来设置/.code，它本身有一个/.@cmd，它最终直接设置/test1/.@cmd属性。希望有所帮助！
答案3
以下是我对这个答案的看法。基本上，设置 a 的.style效果就是设置.@cmd为代码\pgfkeysalso{<keys>}。我认为这是定义“是一种风格”，因为没有办法检查这种代码不是通过.code直接设置产生的，但是，如果它像鸭子一样嘎嘎叫......
我提供了三个用户命令：
\pgfkeysifstyle{<full key>}{<true>}{<false>}，其依据是键是否是上述意义上的样式。\lastpgfkeysstyle，如果键是样式，则存储样式的内容。如果不是，则不要使用它。\pgfkeysifstyleempty（相同的参数），根据样式是否为空来执行操作。如果不是样式，我会选择“true”，否则您可能想要使用\lastpgfkeysstyle。
代码：
\documentclass{article}
\usepackage{filecontents}
\begin{filecontents*}{pgfkeys-ifstyle.sty}
\RequirePackage{etoolbox}% for \ifstrequal, \ifdefempty
\def\lastpgfkeysstyle{}
% Checks if #1 = \pgfkeysalso{...} and, if so, puts the argument
% in \lastpgfkeysstyle
\def\@ifgetpgfkeysalso#1\pgfkeysalso#2#3\@nil{%
\ifstrequal{#1.#3}{.\pgfkeysalso{}}% \pgfkeysalso{#2} is the only thing there
{\def\lastpgfkeysstyle{#2}\@firstoftwo}
{\@secondoftwo}%
}
% So I don't need to write this again
\def\expandaftertwice{\expandafter\expandafter\expandafter}
\def\pgfkeysifstyle#1{%
% "Expand" the key's .@cmd until its code shows
% Even if there is no .@cmd, we get #1\pgfeov, which will not screw us up.
\toks0=\expandaftertwice{\csname pgfk@#1/.@cmd\endcsname##1\pgfeov}%
\expandafter\@ifgetpgfkeysalso\the\toks0 \pgfkeysalso{}\@nil% That space is very important!
}
\def\pgfkeysifstyleempty#1{%
\pgfkeysifstyle{#1}
{\ifdefempty{\lastpgfkeysstyle}}
{% We count a non-style as empty, since otherwise you might use \lastpgfkeysstyle
\PackageWarning{pgfkeys-ifstyle}
{In \noexpand\pgfkeysifstyleempty\MessageBreak
The key #1 is not defined as a style!\MessageBreak}
\@firstoftwo
}%
}
\end{filecontents*}
\usepackage{pgfkeys-ifstyle}
\usepackage{pgfkeys,pgffor}
\begin{document}
\pgfkeys{
/key 1/.style = {x, y, z},
/key 2/.code = {Not a style #1},
/key 3/.initial = {Not even a code},
/key 4/.style = {},% Empty style
/key 5/.code = {\pgfkeysalso{a, b, c} and other stuff},
/key 6/.code = {\pgfkeysalso{a, b, c}},
}
\newcommand*\teststyle[1]{%
\par\medskip\noindent
\pgfkeysifstyle{#1}{#1 has a style: \lastpgfkeysstyle}{#1 is not a style}\\
\pgfkeysifstyleempty{#1}{#1 has an empty style}{#1 does not have an empty style}
}
\foreach \n in {1,...,6} {\teststyle{/key \n}}
\end{document}