I like it but with some caveats. In
rows.setvirtualfields(total=ComputedFields())
we need to specify total to clarify the table or virtualtable the
virtualfields are attached to.
when attaching virtualfields to a table there is no need to specify
that.
So I think it should just be:
table.addvirtualfields(ComputeFields())
Implementation:
The argument would be appended to
table._virtualfields=[]
and the latter would be precessed by
Set.parse
that for each element table._virtualfields would call
setvirtualfields