Abstract type: Difference between revisions
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};</lang> |
};</lang> |
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Because C++ allows multiple inheritance of classes, no distinction is made between interfaces and abstract classes. |
Because C++ allows multiple inheritance of classes, no distinction is made between interfaces and abstract classes. |
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=={{header|Caché ObjectScript}}== |
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In Caché, abstract and data type classes cannot be instantiated directly - there must be a 'concrete subclass' that extends them as well as the '%RegisteredObject' class in order to instantiate an object, see example below. |
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<lang cos>Class Abstract.Class.Shape [ Abstract ] |
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{ |
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Parameter SHAPE = 1; |
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Property Name As %String; |
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Method Description() {} |
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} |
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Class Abstract.Class.Square Extends (%RegisteredObject, Shape) |
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{ |
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Method Description() |
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{ |
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Write "SHAPE=", ..#SHAPE, ! |
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Write ..%ClassName()_$Case(..%Extends(..%PackageName()_".Shape"), 1: " is a ", : " is not a ")_"shape" |
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} |
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}</lang> |
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Data type classes differ because they cannot contain properties, see example below. |
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<lang cos>Class Abstract.DataType.Shape [ ClassType = datatype ] |
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{ |
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Parameter SHAPE = 1; |
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Method Description() {} |
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} |
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Class Abstract.DataType.Square Extends (%RegisteredObject, Shape) |
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{ |
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Method Description() |
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{ |
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Write "SHAPE=", ..#SHAPE, ! |
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Write ..%ClassName()_$Case(..%Extends(..%PackageName()_".Shape"), 1: " is a ", : " is not a ")_"shape" |
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} |
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}</lang> |
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Both class types can contain implementation code. Caché allows multiple inheritance of classes, so no distinction is made between abstract classes and interfaces. |
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{{out|Examples}} |
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<pre> |
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USER>Do ##class(Abstract.Class.Square).%New().Description() |
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SHAPE=1 |
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Square is a shape |
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USER>Do ##class(Abstract.DataType.Square).%New().Description() |
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SHAPE=1 |
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Square is a shape |
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</pre> |
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=={{header|Clojure}}== |
=={{header|Clojure}}== |
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