Scope and metaprogramming in Ruby programming

Scope and metaprogramming in Ruby programming

Scope is an important concept in programming, which defines the visibility and accessibility of variables in the program. Ruby is a dynamic, object-oriented programming language with flexible scoping rules and powerful metaprogramming capabilities. In this article, we'll take a deep dive into scoping and metaprogramming in Ruby and provide corresponding source code examples.

Scope refers to the visible range of variables in a program. There are four different scopes in Ruby: top-level scope, class scope, module scope and method scope. The top-level scope is the outermost scope of a program where variables defined are visible throughout the program. Class scope refers to variables defined in the class definition and they are only visible inside the class. Module scope is similar to class scope, but used to define modules. Method scope refers to the variables defined in the method definition, which are only visible inside the method.

Let's start with a simple example illustrating scoping rules and variable accessibility in Ruby with a source code example:

    x = 10 # 顶级作用域
    
    class MyClass
      y = 20 # 类作用域
    
      def my_method
        z =