如何在 R Z531704A02607A1646EFCF4C1FAE1EEC6 中实现 OOPS class object

Question

I want to implement an OOPS concept similar to building a class object with private data members in R shiny application. How can I do that?

Answer 1

R is a functional language that uses concepts of OOPs. OOPs provides classes and objects as its key tools to reduce and manage the complexity of the program. An object is also called an instance of a class and the process of creating this object is called instantiation. There are two important classes in R which are as follows:

S3 class

does not have a predefined definition and able to dispatch. In this class, the generic function makes a call to the method. Easy implementation of S3 is possible because it differs from the traditional programming language Java, C++, and C# which implements Object Oriented message passing.

In the following code a Student class is defined. Appropriate class name is given having attributes student's name and roll number. Then the object of student class is created and invoked.

# List creation with its attributes name and roll no. 
a <- list(name = "Adam", Roll_No = 15 )   
  
# Defining a class "Student" 
class(a) <- "Student"  
  
# Creation of object 
a 

S4 Class

S4 class has a predefined definition. It contains functions for defining methods and generics. It makes multiple dispatches easy. This class contains auxiliary functions for defining methods and generics.

# Function setClass() command used  
# to create S4 class containing list of slots. 
setClass("Student", slots=list(name="character",  
                               Roll_No="numeric")) 
  
# 'new' keyword used to create object of class 'Student'    
a <- new("Student", name="Adam", Roll_No=20)   
  
# Calling object 
a