[Gretl-devel] Re: bug with "const" in function

Right, but that happens automatically within any given gretl process, regardless of whether any series, or list of series, is passed to the called function. As a trivial illustration: .... In the MPI context the dataset (if present) is not automatically passed between distinct gretl processes, but this is ensured by the --send-data option for a mpi block. Another trivial illustration:

There's one gotcha to note here. If you don't need to pass the entire dataset in the MPI context you can use --send-data=L, where L is a list of series, BUT this won't work if L contains just const. That's because inter-process transfer of data is done using a gdt or gdtb file, and "const" is not explicitly represented in such a file. Trying to save a gdt[b] file containing no series other than const will fail with the message "No data to save!". It's fine if L contains just a single series, but it can't be series 0.

You could insert "list L = index" before the mpi block above, and make the option --send-data=L.

Anyway, the behavior you found with exists() is clearly wrong, and I'm satisfied that a proper fix can be engineered: we'll give the called function a copy of const under the parameter name rather then doing the "shift and rename" thing. That should be in git quite soon.