softFail
abstract fun softFail(category: KbSoftFailEvent.Category, problem: String, input: KbTransformable?): KbTransformable?(source)
Reports a soft failure for the value currently being transformed and returns null to propagate the missing value.
Built-in and custom transforms call this in place of a bare return null when the input or an argument is unsuitable for the operation, so the failure can be observed through the environment's KbEventListener.
Return
always null.
Parameters
category
the kind of soft failure.
problem
a short human-readable description of the problem (for example, "abs: non-numeric input").
input
the value that triggered the failure (typically the transform's input); may be null.