[QGIS-Developer] Processing 3.0: Using expressions instead of fields and values where possible

[Alexander Bruy]

One of the improvements in Processing is support for expressions-based
parameters. But from what I can see this new feature is not widely adopted in
algorithms. For example, algorithms such as SetZValue, SetMValue and many
others still use numeric or field parameters while using expressions
will give them
more flexibility, e.g. taking values from field, formulas etc.

Should we rethink this and move to expressions-based parameters
where possible now when number of adopted algorithms is relatively small?

-- 
Alexander Bruy