Starting with Ruby Metaprogamming

Metaprogramming is a programming technique in which computer programs have the ability to treat programs as their data. It means that a program can be designed to read, generate, analyze or transform other programs, and even modify itself while running.(wikipedia)
 Using simple code samples let's give basic start to metaprogramming which helps to relate how code base can be simplified.
 Considering the below class.

	class Employee
	attr_accessor :emp_id, :emp_name, :emp_designation, :emp_department
	end
	emp_data = { emp_id: 1, emp_name: "Employee1", emp_designation: "Level1", emp_department: "Manufacturing"}
	emp_obj = Employee.new
	emp_obj.emp_id = emp_data[:emp_id]
	emp_obj.emp_name = emp_data[:emp_name]
	emp_obj.emp_designation = emp_data[:emp_designation]
	emp_obj.emp_department = emp_data[:emp_department]
	puts emp_obj.inspect
	Output:
	#<Employee:0x007f8bb0910b20 @emp_id=1, @emp_name="Employee1", @emp_designation="Level1", @emp_department="Manufacturing">

view raw employee.rb hosted with ❤ by GitHub

Now, using some metaprogramming concepts above code can be modified, notice the assign_attributes method used while the o/p in both the examples is same

	class Employee
	attr_accessor :emp_id, :emp_name, :emp_designation, :emp_department
	def assign_attributes(emp_data)
	emp_data.each do |k,v|
	self.send("#{k}=", v)
	end
	end
	end
	emp_data = { emp_id: 1, emp_name: "Employee1", emp_designation: "Level1", emp_department: "Manufacturing"}
	emp_obj = Employee.new
	emp_obj.assign_attributes(emp_data)
	puts emp_obj.inspect
	Output:
	#<Employee:0x007fb959904768 @emp_id=1, @emp_name="Employee1", @emp_designation="Level1", @emp_department="Manufacturing">

view raw employee_meta.rb hosted with ❤ by GitHub

Adding some more examples, below simple code helps to generate methods on the fly instead of defining in individually

	class Employee
	attr_accessor :emp_id, :emp_name, :emp_designation, :emp_department
	def assign_attributes(emp_data)
	emp_data.each do |k,v|
	self.send("#{k}=", v)
	end
	end
	end
	emp_data = { emp_id: 1, emp_name: "Employee1", emp_designation: "Level1", emp_department: "Manufacturing"}
	emp_obj = Employee.new
	emp_obj.assign_attributes(emp_data)
	puts emp_obj.inspect
	Output:
	#<Employee:0x007fb959904768 @emp_id=1, @emp_name="Employee1", @emp_designation="Level1", @emp_department="Manufacturing">

view raw employee_meta.rb hosted with ❤ by GitHub

Metaprogramming should be used with caution and not make the code complicated and difficult to read. It should be easy to understand and modular to change in future.