FWD » Core Development » Base Language

4GL allows a case like:

do:
  catch ex as progress.lang.apperror:
  end.
end.

message ex.

Currently, the FWD conversion looks like:

         doBlock(TransactionType.SUB, "blockLabel0", onPhrase0, new Block(
                  (Init) () ->
         {
            catchError(BaseError.class, (ex) ->
            {
                // the block code here
            });
         },
                  (Body) () -> 
         {
            message("e");
            undoThrow("blockLabel0", e);
         }));

See how the ex member is hidden in the lambda expression. We need to expose this to the parent block.

The good news is that the scope of the ex var is at the parent block, so we can just define a member there.

Greg Shah wrote:

Constantin: Can you link us to the discussion of your fix (and the revision of 4231b in which the fix was added)?

Fixed in rev 4231b rev 11517, "The exception var in a CATCH statement must be defined too, with a _top suffix, to be referenced from the top-level block.".

This was part of #4401-41 work, this comment:

repeat:
   catch errImport as Progress.Lang.Error :
      message string(errImport).
   end.
end.

delete object errImport.

We need to define errImport at the lambda AND at the top-level block. The names must be different, and at the lambda we need to do topVarDef.assign(lambdaRef).