Re: streamDevice redirection-to-records & PVs that start with a number

[Dirk Zimoch <dirk.zimoch@psi.ch>]

Hi Kevin,

I have found the problem. It is an unexpected feature of dbNameToAddr 
combined with the way I resolve the record reference.

In StreamDevice %(redirect) can be %(record), %(record.field) or 
$(field), with the first meaning record.VAL and the last meaning 
current_record.field. So I first check if there is a '.' in the 
reference. In that case it's record.field.

If not, I first try if it's a field of the current record by calling 
dbNameToAddr("current_record.redirect").

In your case this should not match, because your redirect is the name of 
another record (starting with a number).

Now the unexpected dbNameToAddr() feature comes into play: If the field 
name does not start with a letter or underscore, it is ignored and 
dbNameToAddr succeeds and returns a reference to the VAL field.

Try this: dbgf existing_record.3whatever

This creates a false match, so that case 3 (record.VAL) is never tested.

I will fix the way how StreamDevice does the matching...


Dirk


On 14.11.2018 00:33, Peterson, Kevin M. via Tech-talk wrote:
> FYI,
>
> I discovered that streamDevice's redirection-to-records feature fails if
> the name of the destination PV starts with a number:
>
>     https://github.com/paulscherrerinstitute/StreamDevice/issues/20
>
> There have been multiple times in the past where streamDevice support
> that used the redirection-to-records feature worked in my development
> IOC but didn't work when I deployed it to a beamline.  This problem
> wasn't discovered then because eliminating redirection from the support
> was easier than troubleshooting the redirection failure.
>
> This problem is very likely to occur at the APS.  The PV prefix for
> development IOCs is often the developer's initials.  The beamlines are
> numbered and the PV prefix for beamline IOCs usually begins with the
> beamline number.
>
> I hope this saves someone else a little frustration.
>
> Kevin