Ytukyg

I wrote the following code to typeset the title page of a paper:

documentclass{amsart}



usepackage[T1]{fontenc}

usepackage[utf8]{inputenc}

usepackage[USenglish]{babel}



begin{document}



title[Title Title Title]{Title Title Title}



begin{abstract}

    Abstract abstract abstract

end{abstract}



maketitle



end{document}

This outputs the following:

However, I wanted to make my title a macro, because I need it elsewhere too:

documentclass{amsart}



usepackage[T1]{fontenc}

usepackage[utf8]{inputenc}

usepackage[USenglish]{babel}



newcommandmytitle{Title title title}



begin{document}



title[mytitle]{mytitle}



begin{abstract}

    Abstract abstract abstract

end{abstract}



maketitle



end{document}

But this now outputs the following:

No way of fiddling got me the capitalization back. E.g. there is no difference in using def. What is happening here and how to fix it?

Unfortunately, amsart uses by default uppercase (a big nuisance). Happily, the fix is simple: load textcase.

documentclass{amsart}



usepackage[T1]{fontenc}

usepackage[utf8]{inputenc}

usepackage[USenglish]{babel}

usepackage{textcase}



newcommandmytitle{Title title title}



begin{document}



title[mytitle]{mytitle}



begin{abstract}

    Abstract abstract abstract

end{abstract}



maketitle



end{document}

Let's see the definition of title

renewcommand*{title}[2]{gdefshorttitle{#1}gdef@title{#2}}

edeftitle{@nx@dblarg

  @xp@nxcsnamestringtitleendcsname}

This is a common trick in the class for telling LaTeX that if the optional argument is missing then the mandatory argument should be supplied instead.

The problem arises when maketitle is processed, which does @settitle:

def@settitle{begin{center}%

  baselineskip14p@relax

    bfseries

uppercasenonmath@title

  @title

  end{center}%

}

OK, we should look at uppercasenonmath:

newcommand{uppercasenonmath}[1]{toks@@emptytoks

  @xp@skipmath@xp@empty#1$$%

  edef#1{{@nxprotect@nx@upprepthetoks@}}%

}

This only expands @title once, so at the end the primitive uppercase is applied to mytitle (it would be a bit long to go into the details). However the class also has

AtBeginDocument{%

  @ifundefined{MakeTextUppercase}{}{letuppercasenonmathaltucnm}%

}

and we find

defaltucnm#1{%

  MakeTextUppercase{toks@{#1}}%

  edef#1{thetoks@}%

}

and this is much better, because MakeTextUppercase does full (protected) expansion of its argument, so your mytitle gets expanded before uppercasing is done.

Too long for a comment

expandafterexpandafterexpandaftertitleexpandafterexpandafterexpandafter[expandaftermytitleexpandafter]expandafter{mytitle}

But @egreg answer is worthwile reading too. :)