add: 将封面页的条件判断用latex3语法改写，使用latex3引用宏包命令失败

coverinfo.sty

+% \ProvidesExplPackage{coverinfo}{2021-9-4}{0.1}{Some things I wrote}
+
 \tl_const:Nn \TitleOne {曲率引擎的研究}% 第一行标题
 \tl_const:Nn \TitleTwo {}% 第二行标题
 \tl_const:Nn \TitleThree {}% 第三行标题

njuthesis.tex

 \documentclass[
-    TitleLength = 1,% 选择标题行数，范围是1~3
+    TitleLength = 2,% 选择标题行数，范围是1~3
 ]{njuthesis}
 
 \addbibresource{njuthesis.bib}

profile/abstract.sty

+% \ProvidesExplPackage{profile/abstract}{2021-9-4}{0.1}{Some things I wrote} 
+
 % 摘要环境
 \NewDocumentEnvironment{abstract} {}
 {%

profile/components.sty

+% \ProvidesExplPackage{profile/components}{2021-9-4}{0.1}{Some things I wrote} 
+
 % 图表位置调整
 \floatsetup[lstlisting]{ % Captions for lstlistings
 	capposition=above,%

profile/cover.sty

+% \ProvidesExplPackage{profile/cover}{2021-9-4}{0.1}{Some things I wrote} 
+
 % 封面下划线
 \cs_new:Npn \cover_underline:nn #1 #2 {
   \uline{\makebox[#1]{#2}}
@@ -20,17 +22,17 @@
     \coverbox:n {题目}
     & \cover_underline:nn {250pt}{\textbf{\songti\TitleOne}} \\
 
-    \ifnum\TitleLength=2 % 标题行数选择
+    \int_compare:nNnTF { \TitleLength } = { 2 }  { 
       \coverbox:n {}
       & \cover_underline:nn {250pt}{\textbf{\songti\TitleTwo}} \\
-    \fi 
-
-    \ifnum\TitleLength=3
+    }{}
+    
+    \int_compare:nNnTF { \TitleLength } = { 3 }  { 
       \coverbox:n {}
       & \cover_underline:nn {250pt}{\textbf{\songti\TitleTwo}} \\
       \coverbox:n {}
       & \cover_underline:nn {250pt}{\textbf{\songti\TitleThree}} \\
-    \fi
+    }{}
   \end{tabular} \\
 
   \begin{tabular}{p{4.2em}cp{4.2em}c}

profile/font.sty

+% \ProvidesExplPackage{profile/font}{2021-9-4}{0.1}{Some things I wrote} 
+
 % 覆盖Ctex字体设置
 \sys_if_platform_windows:TF
 {

profile/packages.sty

+% \ProvidesExplPackage{profile/packages}{2021-9-4}{0.1}{Some things I wrote} 
+
 \RequirePackage{ifxetex}
 \RequirePackage{lastpage}
 \RequirePackage{fancyhdr}

profile/page.sty

+% \ProvidesExplPackage{profile/page}{2021-9-4}{0.1}{Some things I wrote} 
+
 \fancypagestyle{plain}{%
    \fancyhead{}               
    \fancyfoot[C]{\zihao{5}\thepage}        

profile/profile.cls

 \ExplSyntaxOn
 
-\input{coverinfo.sty}
+\input{coverinfo.sty} 
 \input{profile/packages.sty}
 \input{profile/font.sty}
 \input{profile/cover.sty}