Displaying & highlighting glossary entries that are not defined yet?

Question

In my document I use the glossariespackage.

When referencing terms, that do not exist in the glossary (yet) the term is simply not displayed. Which IMHO forces a quite complex workflow.

Is there any possibility of displaying non-defined terms, but in a different color?

for example:

\gls{DefinedTerm} would be displayed in my default link-color and

\gls{UndedinfedTerm} would be displayed in another style, like red, underlined.

----UPDATE-----

The following does exactly what i was looking for:

\newcommand{\mygls}[1]{\ifglsentryexists{#1}{\gls{#1}}{\textcolor{red}{\underline{#1}}}}

put this in your preamble and simply use \mygls{Term}. Undefined terms will then be highlighted, while defined terms will be displayed using \gls{}

(see JMs answer)

Answer 1

--UPDATE--

I have updated the command as follows (you must include the xcolor pacakage in order to use the \textcolor command:

\let\originalgls\gls
\renewcommand{\gls}[1]{\ifglsentryexists{#1}{\originalgls{#1}}{\textcolor{red}{\underline{#1}}}}

You can now use the \gls command for all your entries, and as you define them, they will switch from being red/underlined to being used as a normal \gls entry.

--END UPDATE--

When I compile my thesis (which I'm in the middle of right now) and I include a \gls{UndefinedTerm} my compilation errors out, stating: "Glossary entry UndefinedTerm has not been defined". Does your compilation not fail? I would encourage you to simply add the terms as you go, it is truly not that cumbersome or time-consuming.

It even appears, looking at glossaries.sty, that it should throw an error (from lines 935-940 of glossaries.sty) To someone more able, this may be the place to modify the code and create the output you need.

\newcommand{\glsdoifexists}[2]{%
  \ifglsentryexists{#1}{#2}{%
    \PackageError{glossaries}{Glossary entry `#1' has not been
    defined}{You need to define a glossary entry before you
    can use it.}}%
}

Otherwise, if all that the \gls for an undefined term will do is print it in red and underline, why not simply make a command for that. You will have to go through the thesis and look for them anyway, then add the entry. I still think that this will be more hassle at the end.

ugls for "Undefined gls" \newcommand{\ugls}[1]{\textcolor{red}{\underline{#1}}}