Experimental Physics and
Industrial Control System

Dirk Zimoch <[email protected]> · Thu, 08 Dec 2011 15:23:07 +0100

Dirk Zimoch wrote:

Hi all,

When I tried to upgrade from 3.14.8 to 3.14.12, I found that some CALC

expressions are not working any more, e.g. "B=0?A"

In 3.14.8 and all previous versions that meant: If B is 0 then set VAL

to A otherwise don't change VAL.

Now, I get the error message:

Unbalanced conditional ?: operators in CALC expression 'B=0?A'
Can't set "recordname.CALC" to "B=0?A"

Was there any good reason for this incompatible change in the CALC

behavior?

Dirk

By the way, the previous behavior is documented here:
http://www.aps.anl.gov/epics/wiki/index.php/RRM_3-14_Calculation#Conditional_Expression

(A+B)<(C+D)?E

    * Result is E if (A+B) < (C+D)

 * Result is unchanged if (A+B) >= (C+D)

The change is not mentioned in the release notes

http://www.aps.anl.gov/epics/base/R3-14/12-docs/RELEASE_NOTES.html

Thus I guess the new behavior was not intended and is a bug.

When fixing this, it is probably worth to implement as well a feature

available in gcc: If the second operand is missing, it is the same as

the first one.

"A+B?:C" means "A+B?A+B:C"  but saves space and cpu cycles.

Dirk

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System