OCLOperators allInstances
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It is a common operator. To find all available you can open the OCL-Editor and type in a class:
=== allInstances () : Set{T} ===
 
Returns a Set containing all of the existing instances of the current classifier (along with instances of all its inherited classifiers).
Your model is central to all expression you will handle. We will use this model to for the examples:
{| class="wikitable"
!Expression
!Result
|-
|let a : String = 'a', b : String = 'b', c : Integer = 2 in String.allInstances()
|Set{'a','b'}
|}
Your model is central to all expressions you will handle. We will use this model for the examples:


[[File:Allinstances operator.png|frameless|355x355px]]
[[File:Allinstances operator.png|frameless|355x355px]]
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|-
|-
|'''Thing.allinstances'''
|'''Thing.allinstances'''
|Gives you a list of all Things
|Gives you a list of all things
|-
|-
|'''Things.allinstances->select(someInt>3)'''
|'''Things.allinstances->select(someInt>3)'''
Line 21: Line 28:
|-
|-
|'''Things.allinstances.Details'''
|'''Things.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 in the list
|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
|-
|-
|'''Things.allinstances.Details.Attribute1'''
|'''Things.allinstances.Details.Attribute1'''
|A list of nullable strings from the contents from the details attribute1. Note that OCL is null-tolerant – you do not need to check if the Details exists of not – the language handles null checks for you
|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'''
|'''SubClassThing1.allinstances.Details'''
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|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
|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
|}
|}
To find all available you can open the OCL-Editor and type in a class:
This was a description of the <code>allinstances</code> operator. It is a common operator. To find all available operators, you can open the OCL Editor and type in a class. See: [[OCLOperators]]
 
[[Category:OCL General Operators]]
[[File:Ocl-editor 1.png|frameless|348x348px]]
{{Edited|July|12|2024}}
 
The operations listed do this:
{| class="wikitable"
!Operators
!Description
|-
|'''Allinstances'''
|All the objects of the class
|-
|'''allinstancesAtTime'''
|All the currently loaded instances
|-
|'''AllStates'''
|Meta information about available states in state machines the class may contain
|-
|'''allSubClasses'''
|Meta information on all the sub classes this class has
|-
|'''AllSuperTypes'''
|Meta information on all the super classes – in inheritance order the class has
|-
|'''associationEnds'''
|Meta information on all the associationEnds
|-
|'''Asstring'''
|The string representation of the class – the asString operation is available on everything
|-
|'''Attributes'''
|Meta information about what attributes the class has
|-
|'''Contraints'''
|Meta information on what constraints the class has
|-
|'''Emptylist'''
|Returns an empty list typed to hold objects of the class
|-
|'''IsDirtyMember'''
|
|-
|'''isNull'''
|
|-
|'''nullValue'''
|A typed null value
|-
|'''objectFromExternalId'''
|An external identity will be resolved to the object
|-
|'''oclAsType'''
|The type of the class
|-
|'''oclIsKindOf'''
|This is to if a class is a subclass or a the class itself and not unrelated
|-
|'''oclIsTypeOf'''
|Returns true if
|-
|'''oclSingleton'''
|Classes that implements the Singleton pattern – by setting IsSingleton=true – will return the singleton instance with this operator
|-
|'''OclType'''
|
|-
|'''safeCast'''
|
|-
|'''SuperTypes'''
|
|-
|'''TaggedValue'''
|Meta information on tagged values set in the class
|-
|'''TaggedValueOnFeature'''
|Meta information on Tagged values set on a named feature in the class
|-
|'''Typename'''
|The type name as a string
|-
|'''ViewModels'''
|A tuple with the ViewModels for this class a members
|}
Once you have a collection of objects there are certain operators that are applicable to it. Again you can use the OCL-Editor to see what they are:
{| class="wikitable"
!Operators
!Description
|-
| ->append
|Add another object last
|-
| ->asBag
|Collapses to one list
|-
| ->asSequence
|Collapses to one list
|-
| ->asset
|Remove doublets
|-
| ->at
|Get the objects at X where the first index is 1
|-
| ->at0
|Get the objects at X where the first index is 0
|-
| ->collect
|Iterate over the collection and build a tuple result
|-
| ->count
|Count how many meet a certain criteria
|-
| ->difference
|The difference between 2 collections
|-
| ->excluding
|The collection except this single object
|-
| ->exists
|Are there any objects that fulfill the criteria
|-
| ->filterOnType
|Only keep the ones of a certain type
|-
| ->first
|Return the first object
|-
| ->forAll
|Iterate all that fulfills the critera
|-
| ->groupBy
|Build collection of tuples grouped by some aspect
|-
| ->includes
|Does the collection include the object
|-
| ->includesAll
|Does the collection include the whole other collection
|-
| ->including
|
|-
| ->IndexOf
|The 1 based index of an object in the collection possibly -1 if not existing
|-
| ->indexOf0
|The 0 based index of an object in the collection possibly -1 if not existing
|-
| ->intersection
|The intersection of two collections
|-
| ->isEmpty
|Returns true if the collection is empty
|-
| ->last
|Returns the last object in the collection
|-
| ->notEmpty
|Returns true of the collection is not empty
|-
| ->orderBy
|Sorts the collection on one or more properties
|-
| ->orderDescending
|Sort the from biggest to smallest
|-
| ->orderGeneric
|Sorts the list of properties with interchangeable sort order: (expr1, OclSortDirection::ascending, expr2, OclSortDirection::descending...)
|-
| ->prepend
|Add an object in front of the list
|-
| ->reject
|Returns the objects not matching the criteria
|-
| ->select
|Returns the objects matching the criteria
|-
| ->size
|Returns the number of elements in the collection
|-
|<nowiki>->subsequence</nowiki>
|Returns a smaller collection from a start to stop
|-
|<nowiki>->symmetricDifference</nowiki>
|The symmetric difference between the collections; ie all the objects in collection1 or collection2 but not in both
|-
| ->union
|The set of objects in collection1 and objects in collection2
|}
One important aspect of OCL that is worth noting is that it expands lists of lists to just a list. An example in plain English; Thing.allinstances.Details – this will come back as a set of details that are all the details from all the Things. If OCL had not expanded lists automatically one could have expected a set of sets containing the details per thing. But this is not the case. The automatically expansion of lists of lists is sometime referred to as flattening of a collection – referring to the reduction of topology in the result.

Latest revision as of 15:40, 10 February 2024

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
let a : String = 'a', b : String = 'b', c : Integer = 2 in String.allInstances() Set{'a','b'}

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

Allinstances operator.png

Operators Description
Thing.allinstances Gives you a list of all things
Things.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
Things.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.
Things.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
Things.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

This page was edited 101 days ago on 02/10/2024. What links here
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