Feature request #9546
|Pull Request or Patch supplied:||No||Resolution:|
|Easy fix?:||No||Copied to github as #:||18133|
There is an increasing number of additional features in expression engine that make sense only in particular context. These features are available either directly in QgsExpression API (e.g. $rownum, $scale) or through "special columns" (e.g. $map, $page, ...). Additionally, with special columns, their value is shared between all QgsExpression instances, which may eventually lead to problems with concurrency (especially with multi-threading).