Access control is a very important part of the object-oriented programming language which is used to restrict the visibility of methods and member fields to protect data from the accidental modification. In terms of access control, Ruby is different from all other Object Oriented Programming languages.
Important Points about Ruby Access Control:
- The visibility of the class variable and instance is always private.
- Access controls are only applicable to methods.
- We can't apply any access control to the instance and the class variables.
- The private methods in Ruby can also be inherited just like public and protected methods.
In Ruby, access control work on two conditions:
- First, from where the method is called, i.e inside or outside of the class definition.
- Second, the self-keyword is included or not. Basically, self-keyword is used to point to the current recipient.
In Ruby, it is not necessary for the inheritance to involve in access control, like in C++ access control are used in inheritance. Access control is of three types as shown in the below image:
👁 Image
Public Method
Public Methods are those methods which can be called by anyone. As we know that access control works only on methods, so
by default all the methods are public. But still, we can define a public method explicitly using the
public keyword. Public methods are generally called outside the class.
Example:
Output:
public method geeks_1 is called
public method geeks_2 is called
public method geeks_3 is called
public method geeks_1 is called
public method geeks_1 is called
Private Method
Private methods are those methods which are not accessible outside the class or in other words, private methods are called only inside the class definition. The methods of the class can access private members. In private methods, we do not use the self-keyword. By default,
initialize method will be private method. The user cannot make the initialize method as the public method. A private method is defined by using
private keyword.
Note: As we know that private methods are strictly restricted for their visibility, only defined class members can access these methods, but they can be inherited by the subclass. A subclass can access them and can override them.
Example:
Error:
source_file.rb:41:in `': private method `geeks_2' called for #
Protected Method
Protected methods can only be called by objects of the defined class and its subclass. The access of these methods is limited in between the defined class or its subclass. You cannot access protected methods outside the defined class or its subclass. The usage of protected methods is finite. Protected methods are defined using
protected keyword.
Example:
Error:
source_file.rb:45:in `': protected method `geeks_2' called for #
Note:
- The user can call the private and protected methods inside a public method of the same class.
Example:
Output:
"Public Method of class Geeks"
"Protected Method of class Geeks"
"Private Method of class Geeks"
- In general, private methods can't be inherited in object-oriented programming languages. But in Ruby, private methods can also be inherited just like protected and public methods.
Example:
Output:
"Public Method of Sudo Class"
"Public Method of class Geeks"
"Protected Method of class Geeks"
"Private Method of class Geeks"
- The public method can be accessed outside the class in which they are defined. But user can't access the private and protected methods outside the class in which they were defined.
Example:
Error:
source_file.rb:54:in `': protected method `method_2' called for #
- The main difference between the protected and private methods is that protected methods are accessible from inside the class by using an explicit receiver while private methods are not.
Example:
Output:
"Public Method of Sudo Class"
"Public Method of class Geeks"
"Protected Method of class Geeks"
"You can't Access!"
- To define multiple protected and private methods in a single class, you can use the following syntax:
class class_name
# this method is public
def public_method
end
public :method_1
protected :method_2, :method_3
private :method_4, :method_5
end
