commands within \subimport

Question

Using a command within subimport leads to problems.

Consider the following files, which have to lay side-by-side in the same folder. test.tex:

\documentclass[]{letter}
\usepackage{import}

\def\AV{510}
\def\AVVers{4}

\begin{document}
The test-values are AV \AV{} V\AVVers{}.
\subimport{}{Test AV \AV{} V\AVVers{}.tex}
%\subimport{}{Test AV 510 V4.tex}

\end{document}

Test AV 510 V4.tex:

17

Using the first, unexpanded call of \subimport, we get the error message

! LaTeX Error: File `Test AV 510{} V4{}.tex' not found.

Using the second, expanded one, we get the expected result, namely

I am aware that LaTeX macros use the first token as argument, such that one should use {} to prevent that the macro devours the first white space after it. But why is the macro evaluated somehow else within \subimport and what do I have to do to prevent it?

Answer 1

TeXnically, you could use a \space instead of {}:

\documentclass[]{letter}
\usepackage{import}

\def\AV{510}
\def\AVVers{4}

\begin{document}
The test-values are AV \AV\space V\AVVers.
\subimport{}{Test AV \AV\space V\AVVers.tex}

\end{document}

The better solution would be to ditch using spaces in file names.