GNU Emacs Manual
U.9 Glasses minor mode
Glasses minor mode makes `unreadableIdentifiersLikeThis'
readable by altering the way they display. It knows two different
ways to do this: by displaying underscores between a lower-case letter
and the following capital letter, and by emboldening the capital
letters. It does not alter the buffer text, only the way they
display, so you can use it even on read-only buffers. You can use the
command M-x glasses-mode to enable or disable the mode in the
current buffer; you can also add
glasses-mode to the mode hook
of the programming language major modes in which you normally want
to use Glasses mode.