ifthenelse adds undesired space

Question

In the following fragment, my use of \ifthenelse in a \newcommand adds a space:

\documentclass[letterpaper]{article}

\usepackage{ifthen}
\usepackage{graphicx}

\newboolean{color-version}
\setboolean{color-version}{false}

\newcommand{\figsubdir}[0]{%
\ifthenelse{\boolean{color-version}}{color}{bw}%
}

\begin{document}

../figures/GAelectrodynamics/\figsubdir/twoParameterDifferentialFig1

\end{document}

In Reducing space after a result of a command I see to add % signs after all the newlines, and I've done so, but it still seems to be there. This shows up more visibly, if the path above is changed to an \includegraphics statement, such as:

\includegraphics[totalheight=0.4\textheight]{../figures/GAelectrodynamics/\figsubdir/twoParameterDifferentialFig1}

With this \includegraphics, the extra rogue space causes a " Missing endcsname inserted." error, and compilation bombs. If I eliminate the ifthenelse use, using an hardcoded macro like:

\newcommand{\figsubdir}[0]{%
bw%
}

Then there is no extra space (and the \includegraphics also works.) But that defeats the purpose of ifthenelse.

Latex version:

• texlive 2019 (Ubuntu 20.04.1, in a Windows WSL2 VM)
• ifthen 2014/09/29 v1.1c Standard LaTeX ifthen package (DPC)

Answer 1

There is no space and I asked TeX in order to confirm it: its response was

....\OT1/cmr/m/n/10 .
....\OT1/cmr/m/n/10 .
....\OT1/cmr/m/n/10 /
....\OT1/cmr/m/n/10 ^^L (ligature fi)
....\OT1/cmr/m/n/10 g
....\OT1/cmr/m/n/10 u
....\OT1/cmr/m/n/10 r
....\OT1/cmr/m/n/10 e
....\OT1/cmr/m/n/10 s
....\OT1/cmr/m/n/10 /
....\OT1/cmr/m/n/10 G
....\OT1/cmr/m/n/10 A
....\OT1/cmr/m/n/10 e
....\OT1/cmr/m/n/10 l
....\OT1/cmr/m/n/10 e
....\OT1/cmr/m/n/10 c
....\OT1/cmr/m/n/10 t
....\OT1/cmr/m/n/10 r
....\OT1/cmr/m/n/10 o
....\kern0.27779
....\OT1/cmr/m/n/10 d
....\OT1/cmr/m/n/10 y
....\OT1/cmr/m/n/10 n
....\OT1/cmr/m/n/10 a
....\OT1/cmr/m/n/10 m
....\OT1/cmr/m/n/10 i
....\OT1/cmr/m/n/10 c
....\OT1/cmr/m/n/10 s
....\OT1/cmr/m/n/10 /
....\OT1/cmr/m/n/10 b
....\kern-0.27779
....\OT1/cmr/m/n/10 w
....\OT1/cmr/m/n/10 /
....\OT1/cmr/m/n/10 t
....\kern-0.27779
....\OT1/cmr/m/n/10 w
....\kern-0.27779
....\OT1/cmr/m/n/10 o
....\OT1/cmr/m/n/10 P
....\kern-0.27779
....\OT1/cmr/m/n/10 a
....\OT1/cmr/m/n/10 r
....\OT1/cmr/m/n/10 a
....\OT1/cmr/m/n/10 m
....\OT1/cmr/m/n/10 e
....\OT1/cmr/m/n/10 t
....\OT1/cmr/m/n/10 e
....\OT1/cmr/m/n/10 r
....\OT1/cmr/m/n/10 D
....\OT1/cmr/m/n/10 i
....\OT1/cmr/m/n/10
                     (ligature ff)
....\OT1/cmr/m/n/10 e
....\OT1/cmr/m/n/10 r
....\OT1/cmr/m/n/10 e
....\OT1/cmr/m/n/10 n
....\kern-0.27779
....\OT1/cmr/m/n/10 t
....\OT1/cmr/m/n/10 i
....\OT1/cmr/m/n/10 a
....\OT1/cmr/m/n/10 l
....\OT1/cmr/m/n/10 F
....\OT1/cmr/m/n/10 i
....\OT1/cmr/m/n/10 g
....\OT1/cmr/m/n/10 1

and we only see implicit kerns between o and d, b and w and so on.

However, the working of \ifthenelse doesn't allow it to do the job you intend to. There are better ways. For instance you could load etoolbox and do

\usepackage{etoolbox}

\newtoggle{color-version}
%\toggletrue{color-version}% uncomment if you want the color version
\newcommand{\figsubdir}{\iftoggle{color-version}{color}{bw}}

or hand make your test:

\newif\ifcoloroutput
%\coloroutputtrue % uncomment if you want the color version
\newcommand{\figsubdir}{\ifcoloroutput color\else bw\fi}

Perhaps more simply

\newcommand{\figsubdir}{bw}
%\renewcommand{\figsubdir}{color}% uncomment if you want the color version