OCLOperators whentrue
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When having immutable ocl expression you always return a value - and the the [[OCLOperators_TrueFalse]] is good, but when using the MDriven Action-Language that allows updates of objects another construct is introduced to compact things even more:
When you have an immutable OCLexpression, you always return a value - and then the [[OCLOperators casetruefalse|OCLOperators_caseTrueFalse]] is good - but when using the MDriven Action-Language that allows updates of objects, another construct is introduced to compact things even more:


boolean.case(dothis):boolean
boolean.whentrue(dothis):boolean


The return is always the arg0
The return is always the arg0


Example:
'''Example:'''
  let x=SomeObject.SomeEnum in (  
  let x=SomeObject.SomeEnum in (  
   (x=#Enum1).case(SomeObject.DoYourThing1);  
   (x=#Enum1).whentrue(SomeObject.DoYourThing1);  
   (x=#Enum2).case(SomeObject.DoYourThing2);  
   (x=#Enum2).whentrue(SomeObject.DoYourThing2);  
   (x=#Enum3).case(SomeObject.DoYourThing3)  
   (x=#Enum3).whentrue(SomeObject.DoYourThing3)  
  )
  )
Fun fact: "case" and logical "and" are implemented the same - the logical "and" only evaluates arg1 of arg0 is true (lazy evaluation) and "case" does the same thing, but always returns arg0.
'''''Fun fact:''''' "whentrue" and logical "and" are implemented the same - the logical "and" only evaluates arg1 of arg0 is true (lazy evaluation) and "whentrue" does the same thing, but always returns arg0.


This means that a convoluted but equivalent construct can be:
This means that a convoluted but equivalent construct can be:
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   (x=#Enum3) and (SomeObject.DoYourThing3;true)  
   (x=#Enum3) and (SomeObject.DoYourThing3;true)  
  )
  )
  [[Category:OCLOperators]]
{{Edited|July|12|2024}}

Latest revision as of 15:43, 10 February 2024

When you have an immutable OCLexpression, you always return a value - and then the OCLOperators_caseTrueFalse is good - but when using the MDriven Action-Language that allows updates of objects, another construct is introduced to compact things even more:

boolean.whentrue(dothis):boolean

The return is always the arg0

Example:

let x=SomeObject.SomeEnum in (  
  (x=#Enum1).whentrue(SomeObject.DoYourThing1);  
  (x=#Enum2).whentrue(SomeObject.DoYourThing2);  
  (x=#Enum3).whentrue(SomeObject.DoYourThing3) 
)

Fun fact: "whentrue" and logical "and" are implemented the same - the logical "and" only evaluates arg1 of arg0 is true (lazy evaluation) and "whentrue" does the same thing, but always returns arg0.

This means that a convoluted but equivalent construct can be:

let x=SomeObject.SomeEnum in (  
  (x=#Enum1) and (SomeObject.DoYourThing1;true);  
  (x=#Enum2) and (SomeObject.DoYourThing2;true);  
  (x=#Enum3) and (SomeObject.DoYourThing3;true) 
)
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