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This constraint specifies that if the <code>name</code> attribute of a product object is null, then its <code>price</code> attribute must be less than or equal to zero (i.e., negative or zero prices are not allowed). If the <code>name</code> attribute is not null, then the constraint does not impose any restriction on the value of the <code>price</code> attribute. | This constraint specifies that if the <code>name</code> attribute of a product object is null, then its <code>price</code> attribute must be less than or equal to zero (i.e., negative or zero prices are not allowed). If the <code>name</code> attribute is not null, then the constraint does not impose any restriction on the value of the <code>price</code> attribute. | ||
[[Category:OCL Boolean Operators]] | [[Category:OCL Boolean Operators]] | ||
{{Edited|July|12|2024}} | |||
Latest revision as of 15:39, 10 February 2024
This operator is represented by the keyword "implies" and is used to express a conditional relationship between two Boolean expressions. The expression "a implies b" is true if either a is false or b is true (or both). In other words, if a is true, then b must also be true for the entire expression to be true. If a is false, then the expression is automatically true regardless of the value of b. For example, "if it's raining (a), then I will bring an umbrella (b)" can be expressed as "a implies b" in OCL.
The "Implies" operator evaluates to true if its first operand is false or its second operand is true, and false otherwise.
Example:
Suppose we have a class called Product with two attributes: name and price. We want to define a constraint that requires the price attribute to be greater than zero if the name attribute is not null. The OCL expression for this constraint would be:
context Product
self.name = null implies (self.price <= 0)
This constraint specifies that if the name attribute of a product object is null, then its price attribute must be less than or equal to zero (i.e., negative or zero prices are not allowed). If the name attribute is not null, then the constraint does not impose any restriction on the value of the price attribute.