allInstances () : Set{T}

Returns a Set containing all of the existing instances of the current classifier (along with instances of all its inherited classifiers).

Expression	Result
Thing.allInstances	all the Thing object instances currently in your system - if only in DB objects will be loaded

Your model is central to all expressions you will handle. We will use this model for the examples:

Operators	Description
Thing.allinstances	Gives you a list of all things
Thing.allinstances->select(someInt>3)	Only things with someInt bigger than 3
Thing.allinstances->select( (someInt>3) and (someInt<6))	Only things with someInt bigger than 3 but less than 6. Notice the extra parenthesis to or the Boolean expressions together
Thing.allinstances->select(x|x.someInt>3)	Here we introduce the loop variable x. We separate the definition of x from the usage of x with the pipe sign “|”. Loop variables are optional but if names are unique – but you will need to use them to give precision or to if you want to perform operations on the loop context itself.
Thing.allinstances.Details	Gives a list of all Detail objects that are connected to a Thing. The Detail objects that float around without a Thing will not be on the list
Thing.allinstances.Details.Attribute1	A list of nullable strings from the contents of the details attribute1. Note that OCL is null-tolerant – you do not need to check if the Details exist or not – the language handles null checks for you.
SubClassThing1.allinstances.Details	Inherited features of classes are directly accessible
Thing.allInstances->select(x|x.safeCast(SubClassThing1). OnlyAvailableInSubClass='Hello')	Filtering on Specialization is done with an operator SafeCast. This is null safe so for all objects that do not fit the profile the expression returns false

This was a description of the allinstances operator. It is a common operator. To find all available operators, you can open the OCL Editor and type in a class.

See: OCLOperators