[Qgis-developer] QgsExpression: Comment support and unary minus

[Matthias Kuhn]

Hi all,

I am working on introducing comment support for QgsExpressions (See
below for examples). Line comments should be started with `--` (double
minus) like in SQL. Running the test suite on this complains, because
there is a test for unary minus that tests if `--1` evaluates properly.
And that would be considered a comment after this change, currently it
evaluates to 1 (Legitimate, but is that useful?).
Question:

 * Is that a typo and it should actually be `-1`?
 * Is there a reason, that `--` as initial delimiter for line comments
is not good?

------------------------
Examples:

Block comments:

    /*
     * Comment
     */

And line comments:

    CASE
      WHEN name = 'QGIS' THEN 'Yay' -- Using the good stuff
      ELSE 'Nay' -- You can get it on http://qgis.org
    END