Status/Resolution/Reason: Closed/Withdrawn/AsDesigned
Reporter/Name(from Bugbase): Adam Cameron / Adam Cameron (Adam Cameron)
Created: 02/19/2014
Components: Language
Versions: 11.0
Failure Type:
Found In Build/Fixed In Build: PublicBeta /
Priority/Frequency: Major / Some users will encounter
Locale/System: English / Platforms All
Vote Count: 1
See http://cfmlblog.adamcameron.me/2014/02/coldfusion-11-good-stuff.html#nullCoalescingOperator
Extract:
The null-coalescing operator is a binary operator that works thus:
result = firstValue ?: secondValue
The rule being that the result will be the firstValue if it is not null, otherwise it will be the second value. Simple. Both Railo and now ColdFusion have messed it up a bit though, confusing the concepts of "null" with "not defined".
This demonstrates the correct operation of the null-coalescing operator:
//nullCoalescingOperatorCorrect.cfm
nullVariable = javaCast("null", "");
variableToSet = nullVariable ?: "default value";
writeDump({variableToSet=variableToSet});
This outputs:
struct
VARIABLETOSET default value
because nullVariable is null, it's not used for the value of variableToSet; "default value" is instead.
However this demonstrates where CFML goes a bit wrong:
// nullCoalescing.cfm
variableToSet = notDefined.invalidProperty ?: "default value";
writeDump({variableToSet=variableToSet});
This should error. Because notDefined isn't null, it's not defined. And something that isn't defined cannot have a property (. operator), so notDefined.invalidProperty is just an error situation. However this "works" in CFML:
struct
VARIABLETOSET default value
I raised this yesterday with Railo: "Probable bug in null-coalescing operator", and Igal and I just got the hump with each other, but Gert is erring towards "right or wrong, I'd prefer 'wrong'". I'd prefer "right". The way to solve it so that everyone is happy would be to additionally implement the safe navigation operator, as I mention in an earlier article: "Thinking about operators in CFML". This way we have the ?. operator acting how it's supposed to, and the ?: acting how it's supposed to. Not implementing ?: so that it alters how the . operator works.
----------------------------- Additional Watson Details -----------------------------
Watson Bug ID: 3710381
External Customer Info:
External Company:
External Customer Name: Adam Cameron.
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