A rare syntax
highlighting problem results from an extremely unfortunate
notation for octal numbers in IDL: "123. This
unpaired quotation mark is very difficult to parse, given that it
can be mixed on a single line with any number of strings. Emacs
will incorrectly identify this as a string, and the highlighting
of following lines of code can be distorted, since the string is
never terminated.
One solution to this involves terminating the mistakenly identified string yourself by providing a closing quotation mark in a comment:
string("305B) + $ ;" <--- for font-lock
' is an Angstrom.'
A far better solution is to abandon this notation for octals altogether, and use the more sensible alternative IDL provides:
string('305'OB) + ' is an Angstrom.'
This simultaneously solves the font-lock
problem and is more consistent with the notation for hexadecimal
numbers, e.g. 'C5'XB.