Existence Operators

Existence Operators perform operations to do with the existence of Variables.

Symbol Type Name Description Example
??? Prefix Existence Returns true if the variable exists, or false otherwise ??? a
destroy Prefix Destruction Destroys the Variable (or Array key) named destroy a

Existence operators will only function on Variables. In particular, an error will be generated if destroy is applied to a Variable that does not exist.

The ERR Logical Operator - |?| - is essentially a convenient, in-line existence check, and is the logical comparison version of ???.

ptpscript/operators/existence.txt · Last modified: 2007/01/24 10:15
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