Re: A question concerning rset->special()

[Andrew Johnson <anj@aps.anl.gov>]

Benjamin Franksen wrote:
> can the record support special() routine find out how many (array) 
> elements have been resp. are going to be written (assuming SPC_MOD is 
> set for the field and there is actually more than one element etc..)? 
> And if yes, how?

No, the arguments to the rset->special() routine are the DBADDR for the 
field that is being written to, and the pass (0 before, 1 after the 
actual put operation).

However if there's more than one element in the buffer and the field is 
marked as special, immediately after calling rset->special() the 
rset->get_array_info() routine is called to get the offset value (for 
appending data to circular buffers), and after changing the array the 
rset->put_array_info() routine is also called to tell it how big the 
request was.  Unfortunately this doesn't seem to provide any way to 
reject a put based on size if that's what you're trying to do.

The code that implements this is dbPut() in src/db/dbAccess.c which 
should be reasonably easy to follow.

- Andrew
--
There is considerable overlap between the intelligence of the smartest
bears and the dumbest tourists -- Yosemite National Park Ranger