questions about \xpatchcmd, \ProcessKeysOptions in l3keys2e package, \ProcessKeysOptions in kvoptions package and \widowpenalties

i use nowidow package and \setnowidow, but some case it work not fine:

for example, i hope paragraph can do page break at red place, but it doesn't.

Then I test, if I change nowidow.sty, make \widowpenalties 2 10000 0 to \widowpenalties 3 10000 -1 0, it can work fine.

\newcommand{\setnowidow}[1][\nowidow@defaultlines]{% \mathchardef\nowidowmax#1\relax % \widowpenalties #1 \nowidow@X{1} 0\par <-- before it's \widowpenalties \numexpr(#1)+1 \nowidow@X{1} -1 0\par % <-- after i change } 

so I try many ways to patch it (not change the nowidow.sty directly), but all failed.

Way1: I use \xpatchcmd, not success:

\xpatchcmd\setnowidow{\widowpenalties #1 \nowidow@X{1} 0\par}{\widowpenalties \numexpr(#1)+1 \nowidow@X{1} -1 0\par}{}{} 

Q1: why it can't success?

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Way2: I try \renewcommand, it also failed: MWE: my main tex test.tex:

\documentclass{book} \usepackage[paper=a5]{zztj} \begin{document} abc \end{document} 

my customed package zztj.sty:

\NeedsTeXFormat{LaTeX2e} \RequirePackage{expl3} \ProvidesExplPackage{zztj}{}{}{} \RequirePackage{l3keys2e} %--- \RequirePackage{nowidow} \renewcommand{\setnowidow}[1][\nowidow@defaultlines]{% \mathchardef\nowidowmax#1\relax \widowpenalties \numexpr(#1)+1 \nowidow@X{1} -1 0\par } \setnowidow % --------my other options-------- \tl_new:N\g__zztj_paper_tl \keys_define:nn{zztj/option} { paper.choices:nn= {a4, a5} {\tl_gset:Nn\g__zztj_paper_tl{#1}}, } \ProcessKeysOptions{zztj/option} 

build error:

! Missing number, treated as zero. <to be read again> \tex_par:D l.15 \tl_new:N \g__zztj_paper_tl ? 

Q2: why have this error?

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Way3: so I copy the source from nowidow.sty, and change it, but can't success also, because I use l3keys2e package also: MWE: my customed package zztj.sty:

\NeedsTeXFormat{LaTeX2e} \RequirePackage{expl3} \ProvidesExplPackage{zztj}{}{}{} \RequirePackage{l3keys2e} % --------start copy from nowidow-------- \RequirePackage{kvoptions} \SetupKeyvalOptions{ family=nowidow, prefix=nowidow@, } \DeclareStringOption[2]{defaultlines} \DeclareBoolOption{all} \ProcessKeyvalOptions* \def\nowidow@X#1{% \ifnum#1<\nowidowmax 10000 \expandafter\nowidow@X\expandafter{% \the\numexpr(#1)+1\expandafter\relax\expandafter}% \fi } \newcommand{\setnowidow}[1][\nowidow@defaultlines]{% \mathchardef\nowidowmax#1\relax \widowpenalties \numexpr(#1)+1 \nowidow@X{1} -1 0\par } \ifnowidow@all \setnowidow \fi \newcommand{\nowidow}[1][\nowidow@defaultlines]{% \begingroup \setnowidow[#1] \endgroup } \newcommand{\setnoclub}[1][\nowidow@defaultlines]{% \mathchardef\nowidowmax#1\relax \clubpenalties \numexpr(#1)+1 \nowidow@X{1} -1 0\par } \ifnowidow@all \setnoclub \fi \newcommand{\noclub}[1][\nowidow@defaultlines]{% \begingroup \setnoclub[#1] \endgroup } % --------end copy from nowidow-------- \setnowidow % --------my other options-------- \tl_new:N\g__zztj_paper_tl \keys_define:nn{zztj/option} { paper.choices:nn= {a4, a5} {\tl_gset:Nn\g__zztj_paper_tl{#1}}, } \ProcessKeysOptions{zztj/option} 

build error:

! Package keyval Error: paper undefined. See the keyval package documentation for explanation. Type H <return> for immediate help. ... l.14 \ProcessKeyvalOptions* 

Q3: why have this error?

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Way4: I input \widowpenalties 3 10000 -1 0 directly, It still can't success: my customed package zztj.sty:

\NeedsTeXFormat{LaTeX2e} \RequirePackage{expl3} \ProvidesExplPackage{zztj}{}{}{} \RequirePackage{l3keys2e} %--- \widowpenalties 3 10000 -1 0 % --------my other options-------- \tl_new:N\g__zztj_paper_tl \keys_define:nn{zztj/option} { paper.choices:nn= {a4, a5} {\tl_gset:Nn\g__zztj_paper_tl{#1}}, } \ProcessKeysOptions{zztj/option} 

build error:

! Missing number, treated as zero. <to be read again> \tex_global:D l.9 \tl_new:N\g__zztj_paper_tl 

Q4: why \widowpenalties still fail?

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Q5: what's the good way to patch the \setnowidow command but don't change the nowidow.sty directly?