\input{} give error when only entering part of a command

input

I have a main.tex file, which in the preamble contains the following path definition

\def\commonpath{C:/Users/Default/Documents/Folder}

This compiles just fine. If I break the code into separate lines as such:

\def\commonpath{%
   C:/Users/Default/Documents/Folder%
}

Everything compiles just fine as well.

What I would like to do is to take the path out into a separate file. For example, I would like to create a file folderpath.tex and place it in the same directory as main.tex. folderpath.tex should contain only the following line:

C:/Users/Default/Documents/Folder

Then, in main.tex I would like to have something like

\def\commonpath{%
   \input{folderpath.tex}%
}

However when I do that and try to compile I get a missing \begin{document} error.

How can I get around this problem? I thought that the \input{} command takes literally the content of the file that is being inputted.

Any help would be appreciated.

Best Answer

You can do this using expl3 rather easily:

\ExplSyntaxOn
\file_get:nnN { folderpath.tex } {} \commonpath
\ExplSyntaxOff
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