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(!$AttributeName) (short form test for no value)


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 Function   [other Function type actions]

 Item   [operators of similar scope]

 Query Boolean   [other Query Boolean operators]

 Baseline

 


(!$AttributeName)

In queries and conditional action code expressions, starting an attribute name preceded by an exclamation mark plus a $ character functions as a shortened form of the Boolean test for a false value. Due to limitations in the underlying parser, an inequality test expression must be enclosed in parentheses.Thus the following are functional equivalents:

$MyBoolean==false 

(!$MyBoolean) 

Do not use this form or you may get unexpected results:

!$MyBoolean Do not use this format, without parentheses!

In both cases the result is false if the value of $MyBoolean is false.

Usefully Tinderbox also useful supports such short-form !$AttributeName tests for all the other attribute data types, returning true if the attribute has a default value. Per data type, this equates to long form tests like:

$MyAction=="" 

$MyColor=="" 

$MyDate==never 

$MyFile=="" 

$MyInterval=="00:00" 

$MyList=="" 

$MyNumber==0 

$MySet=="" 

$MyString=="" 

$MyURL=="" 

In all these cases a short-form test returns true if the attribute value is the default for that data type.

This test is the logical opposite of the $AttributeName test.



A Tinderbox Reference File : Actions & Rules : Operators : Full Operator List : (!$AttributeName) (short form test for no value)