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Version: 4.x

CLASS operator

The CLASS operator creates a property that implements a matching signature operator.

Syntax​

CLASS(expr)

Description​

The CLASS operator creates a property that determines whether or not, from a class perspective, a specified property can have a non-NULL value for passed arguments.

Parameters​

  • expr

    An expression whose result is a property. For this property, a set of parameter classes is inferred, matching which is checked by the result property.

Examples​

CLASS A;
a = ABSTRACT CASE STRING[100] (A);

CLASS B : A;
b = DATA STRING[100] (B);

a(B b) += WHEN CLASS(b(b)) THEN b(b); // is equivalent to WHEN b IS B THEN b(b)