Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Thu, 21 Aug 2008 09:40:27 -0500

On Thursday 21 August 2008 02:32:45 Dirk Zimoch wrote:
>
> I think, the two headers were supposed to be "private" to cas. But since
> the gateway needs them the base Makefile should be modified to install
> them. That's what I did and it works fine. However I didn't try 3.14.9. but
> run with 3.13.8.2.

The latest version of the gateway in CVS has the following added to the 
gateway/Makefile which completely avoids the need to install those files:

# need access to casCtx.h
USR_INCLUDES += -I$(EPICS_BASE)/src/cas/generic

This method also makes it a little more obvious that the gateway code is using 
private APIs inside CAS that could change as the CAS implementation changes.

> I have added a bug report to Mantis
> (http://www.aps.anl.gov/epics/mantis/main_page.php).
>
> Someone could add that information to the gateway documentation. :-)

For maintainability reasons I much prefer that we modify CAS to make the 
necessary API routines or their equivalents available through the official 
headers.  Installing or using private headers makes the innards of the CAS 
implementation visible to applications, which means that future changes to 
the implementation of CAS can break the external code that has started using 
these private APIs.  I'm sure Jeff will agree with me on this point.

Unfortunately this issue has surfaced too late for any changes to CAS to be 
included in R3.14.10, but I hope that we'll be able to work something out 
soon afterwards and provide a patch file for CAS to be used when building the 
gateway until the next Base release.

Dirk, these headers were added by your patch to the gateway that Janet applied 
last year, can you explain to Jeff what functionality you need from CAS.

- Andrew
-- 
Talk is cheap. Show me the code. -- Linus Torvalds

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System