The type OclVoid is a type that conforms to all other types except OclInvalid.
It has one single instance, identified as
null
, that corresponds with the UML LiteralNull value specification.
Any property call applied on
null
results in
invalid
, except for the
oclIsUndefined(), oclIsInvalid(), =(OclAny) and <>(OclAny) operations.
However, by virtue of the implicit conversion to a collection literal,
an expression evaluating to
null
can be used as source of collection operations (such as ‘isEmpty’).
If the source is the
null
literal, it is implicitly converted to Bag{}.
OclVoid is itself an instance of the metatype VoidType.
conformsTo
OclAny
Operations
allInstances() : Set(OclSelf)
Returns
Set{null}
.
=(object2 : OclSelf) : Boolean
precedence:
EQUALITY
Redefines the OclAny operation, returning
true
if object is
null
,
invalid
if object is
invalid
,
false
otherwise.
<>(object2 : OclSelf) : Boolean
precedence:
EQUALITY
and(b : Boolean) : Boolean
precedence:
AND
implies(b : Boolean) : Boolean
precedence:
IMPLIES
or(b : Boolean) : Boolean
precedence:
OR
toString() : String
Returns
null
.