polymorphism

问题 Does java support multiple dispatch? If not how is the below code working? Account.java public interface Account { public void calculateInterest(); } SavingsAccount.java public class SavingsAccount implements Account { } LoanAccount.java public class LoanAccount implements Account { } InterestCalculation.java public class InterestCalculation { public void getInterestRate(Account objAccount) { System.out.println("Interest Rate Calculation for Accounts"); } public void getInterestRate

问题 Does java support multiple dispatch? If not how is the below code working? Account.java public interface Account { public void calculateInterest(); } SavingsAccount.java public class SavingsAccount implements Account { } LoanAccount.java public class LoanAccount implements Account { } InterestCalculation.java public class InterestCalculation { public void getInterestRate(Account objAccount) { System.out.println("Interest Rate Calculation for Accounts"); } public void getInterestRate

问题 The following snippet was from (https://stackoverflow.com/a/37461290/2129302): tensor : Vect n Nat -> Type -> Type tensor [] a = a tensor (m :: ms) a = Vect m (tensor ms a) I'd like to define the following: mkStr : (Show a) => tensor shape a -> String mkStr x = show x But instead this gives the following error: Can't find implementation for Show (tensor shape a) However, on the REPL I can run "show [some tensor value...]". Why is this and what can I do to fix it? 回答1: You're not showing a ,

问题 The following snippet was from (https://stackoverflow.com/a/37461290/2129302): tensor : Vect n Nat -> Type -> Type tensor [] a = a tensor (m :: ms) a = Vect m (tensor ms a) I'd like to define the following: mkStr : (Show a) => tensor shape a -> String mkStr x = show x But instead this gives the following error: Can't find implementation for Show (tensor shape a) However, on the REPL I can run "show [some tensor value...]". Why is this and what can I do to fix it? 回答1: You're not showing a ,

问题 I want to create an array of polymorphic objects which have constructors taking different dummy arguments depending on their dynamic type. Having read about user-defined and structure constructors, I see no way to apply these concepts to dynamically allocated objects. Having a background in C++, I was used to the notion that I could use one and the same constructor "member function" when allocating objects either dynamically or on the stack, but how can I explicitly call user-defined Fortran

问题 Look, I know static classes can't inherit or implement. The question is "what the heck is the right C# + OOP pattern to implement this?". "This" is described below: I want to define a common set of both definition and implementation for a group of classes where all but one type should be static. Namely, I want to make some arbitrary base converters where each have exactly the same four members: // Theoritical; static classes can't actually implement interface IBaseConverter { int Base { get;

问题 Look, I know static classes can't inherit or implement. The question is "what the heck is the right C# + OOP pattern to implement this?". "This" is described below: I want to define a common set of both definition and implementation for a group of classes where all but one type should be static. Namely, I want to make some arbitrary base converters where each have exactly the same four members: // Theoritical; static classes can't actually implement interface IBaseConverter { int Base { get;

问题 I know the title's statement is true. What about a regular function? For example class Father { virtual void foo() {...;} } class Son : public Father { void foo() {...;} } class GrandSon : public Son { void foo() {...;} } Can GrandSon override Son's foo? In general, if your base class has a virtual function, the derived class's corresponding function is automatically virtual? Is this true? 回答1: Yes, in C++ a derived class "inherits" the virtual aspect of all methods--not just destructors. 回答2

问题 The Liskov Substitution Principle states: Invariants of the supertype must be preserved in a subtype. I'm particularly interested with the intersection of this principle and polymorphism. In particular subtype-polymorphism though, in fact, this seems to be the case with parametric polymorphism and Haskell type classes. So, I know that functions are subtypes when their arguments are contravariant and their return types covariant. We can assume that methods are just functions with an implicit

问题 The Liskov Substitution Principle states: Invariants of the supertype must be preserved in a subtype. I'm particularly interested with the intersection of this principle and polymorphism. In particular subtype-polymorphism though, in fact, this seems to be the case with parametric polymorphism and Haskell type classes. So, I know that functions are subtypes when their arguments are contravariant and their return types covariant. We can assume that methods are just functions with an implicit