My answer is still the same since i read your question and understood it pretty well:
You can generate the fieldcatalog even if you use dynamic ALV or get it after the alv generation if you use classes like CL_GUI_ALV_GRID (i suggest to change the technology you use)
Once you get it, you can change and set it to alv (replacing texts with tech names i.e.)
If you "got a table provided in selection screen", you can read the dictionary and create the fieldcat according to it before showing ALV.
And again, what did you try yourself?
And it was you writing that you use REUSE_ALV_FIELDCATALOG_MERGE !
Satish Kumar Balasubramanian wrote:
Am using FM REUSE_ALV_FIELDCATALOG_MERGE to build the field catalog
and then
Satish Kumar Balasubramanian wrote:
It is a dynamic ALV generation concept, and we don't generate field catalog in the code.
So, if you use REUSE_ALV_FIELDCATALOG_MERGE you got fieldcatalog available.