delete-selection-mode and $

Question

Using Aquamacs 3.2 on Mac OSX Yosemite. I run with delete-selection-mode set, and it mostly works as advertised. However, if I'm in TeX mode (AucTeX), make a selection, and then type $, the selection is cleared and the $ appended. So for example if I select foobar in xyzfoobarxyz and type $, I get xyzfoobar$xyz instead of the desired xyz$xyz. Is this known/documented behavior, or a bug? If it's a bug, is it an AucTeX or an Aquamacs issue (or an Emacs issue)?

Edit: In response to Tobias' comment below, C-h k $ returns

$ runs the command TeX-insert-dollar, which is an interactive compiled Lisp function in `tex.el'.

It is bound to $.

(TeX-insert-dollar &optional ARG)

Insert dollar sign.

If current math mode was not entered with a dollar, refuse to insert one. Show matching dollar sign if this dollar sign ends the TeX math mode and 'blink-matching-paren' is non-nil. When outside math mode, the behavior is controlled by the variable 'TeX-electric-math'.

With raw ^U prefix, insert exactly one dollar sign. With optional ARG, insert that many dollar signs.

And, the function delete-selection-mode is defined in delsel.el.

I'm far from LISP-literate. Perhaps the TeX-insert-dollar function does not take the delete selection mode into account (either by design or by omission)?

Answer 1

AUCTeX provides the feature to wrap opening and closing inline equation markers around active region on pressing $, when TeX-electric-math is non-nil (and this isn't the default). In order to have this, the delete-selection property had to be removed. Actually, its behavior can be dynamically determined by a function, so that

(put 'TeX-insert-dollar 'delete-selection (lambda () (null TeX-electric-math)))

enables or disables it depending on the value of TeX-electric-math. Thanks to this discussion, the above line is now present also in development version of AUCTeX.