ln014 - Polymorphism A closer look at types polymorphism...

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Polymorphism Chap 8 polymorphism comes from Greek meaning ‘many forms’ In programming: Def : A function or operator is polymorphic if it has at least two possible types. A closer look at types ....
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Polymorphism i) Overloading Def: An overloaded function name or operator is one that has at least two definitions, all of different types. Example : In Java the ‘+’ operator is overloaded. String s = “abc” + “def”; int i = 3 + 5; +: String * String String +: int * int int
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Polymorphism Example : Java allows user defined polymorphism with overloaded function names. bool f (char a, char b) { return a == b; } bool f (int a, int b) { return a == b; } f : char * char bool f : int * int bool Note: ML does not allow function overloading
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Polymorphism ii) Parameter Coercion Def : An implicit type conversion is called a coercion . Coercions usually exploit the type-subtype relationship because a widening type conversion from subtype to supertype is always deemed safe a compiler can insert these automatically type coercions.
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