I did some tests with the ?: syntax.
Even though unbalanced ?: are generally not valid, unbalanced
sub-expressions are accepted and do interesting things.
"(A?B):C" and "A?(B:C)" are accepted and work like "A?B:C"
"SIN(A?B):C" is accepted and works like "A?SIN(B):C"
"A?SIN(B:C)" is accepted and works like "SIN(A?B:C)"
That has not exactly the same effect. The old syntax "A?B" raised a
CALC/INVALID alarm when A is false. The INVALID can be checked for with
IVOA and can be passed to other records with MS links. I do not see a
full replacement for this behavior.
You can add ":VAL" to fix old expressions
Andrew Johnson wrote:
On 2011-12-08 Dirk Zimoch wrote:
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
Yes, it was really obscure; I didn't know it worked at the time, let alone
that it was documented. There was certainly nothing in the code to indicate
that it was meant to be legal.
You can add ":VAL" to fix old expressions, which in 3.14.12 and later can be
up to 79 characters long.
The change is not mentioned in the release notes
Thus I guess the new behavior was not intended and is a bug.
The change was part of a major rewrite of the CALC expression parser that was
released as part of 3.14.9 in 2007. Making this legal again would IMHO be a
backwards step since there is an easy fix for old expressions and the results
are easier to understand.
Sorry, that's just another change you'll have to make when upgrading.
- Unbalanced conditional ? Dirk Zimoch
- Re: Unbalanced conditional ? Dirk Zimoch
- Re: Unbalanced conditional ? Andrew Johnson
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