Some packages (ntheorem for example) take only text switches as arguments that can be used in the form {\switch text}, for example \bfseries. If I now want to have a suitable command for underlining, the \underline command does not work, as it requires the argument explicitly using parentheses.
To make this clearer, I would like to convert something like
\underline{lorem ipsum}
to the form
{\ulswitch lorem ipsum}
latex-projecttag is really just about the develop project of LaTeX. You don't need to tag a question for LaTeX, that's the default here. – Martin Scharrer Dec 19 '11 at 22:23\underlinefor text, because it is only intended for math. Use\ulinefromulemas I show in my answer or the corresponding macro fromsoul. – Martin Scharrer Dec 19 '11 at 22:35ulem, but I thought\underlinewould make the question clearer. – David Dec 19 '11 at 22:37