Expanding to separate letters or capitalizing first letter of macro result

Question

The following code produces Die Patientin ist nicht die Patientin. I'd like to have the second die also capitalized.

Using \edef for \p@tcnom the whole argument is capitalized instead of only the first letter.

This is different from this question since \p@tctst already solves that issue. So it's similar, but another level of indirection. ;)

Could some TeX wizard please shine a light on this?

\documentclass{article}

\def\ucletter{\expandafter\makeupcase}
\def\makeupcase#1{\uppercase{#1}}
\newif\ifmale

\makeatletter
\def\p@tctst{die Patientin}
\def\p@tcnom{\ifmale{der Patient}\else{die Patientin}\fi}
\def\mytesti#1{\ucletter\p@tctst}
\def\pattest#1{\ucletter\p@tcnom}
\makeatother

\begin{document}

\mytesti{void} ist nicht \pattest{void}.

\end{document}

Answer 1

If you add \tracingmacros=1 just before the use of \pattest you'll see in the log file what actually happens. Mine shows the following:

\pattest #1->\ucletter \p@tcnom 
#1<-void

\ucletter ->\expandafter \makeupcase 

\p@tcnom ->\ifmale der Patient\else die Patientin\fi 

\makeupcase #1->\uppercase {#1}
#1<-\ifmale 

...

This means that \makeupcase is applied to the \ifmale token and not to the expanded string. So another expansion is necessary, for which \expandafter before \ucletter would help.

Another issue is with the braces. When you replace the \pattest definition by \def\pattest#1{\expandafter\ucletter\p@tcnom} you'll get the following (againg in the log):

\pattest #1->\expandafter \ucletter \p@tcnom 
#1<-void

\p@tcnom ->\ifmale {der Patient}\else {die Patientin}\fi 

\ucletter ->\expandafter \makeupcase 

\makeupcase #1->\uppercase {#1}
#1<-die Patientin

...

So the braces group the letters and make the whole word an argument to \makeupcase. That's why all the letters switch case. You'll have to remove the braces.

Also, I don't really understand why do you define \pattest with an argument which is thrown away then, but it's irrelevant for the problem here.

The following code is a minimal modification of your MWE which produces the correct output with only the first letter is uppercased:

\documentclass{article}

\def\ucletter{\expandafter\makeupcase}
\def\makeupcase#1{\uppercase{#1}}
\newif\ifmale

\makeatletter
\def\p@tctst{die Patientin}
\def\p@tcnom{\ifmale der Patient\else die Patientin\fi}
\def\mytesti#1{\ucletter\p@tctst}
\def\pattest#1{\expandafter\ucletter\p@tcnom}
\makeatother

\begin{document}

\mytesti{void} ist nicht \pattest{void}.

\end{document}