I found a blog post about alias alias_method. As the example in this blog post shows, I just want to alias another method in the same class. Which should I use? I always see using alias, but someone told me that alias_method is better.

Use of aliases

class User

  def full_name
    puts "Johnnie Walker"
  end

  alias name full_name
end

User.new.name #=>Johnnie Walker

Usage of alias_method

class User

  def full_name
    puts "Johnnie Walker"
  end

  alias_method :name, :full_name
end

User.new.name #=>Johnnie Walker

Blog post link here

#1 building

Although it may not be big, I like aliases for two things, rather than alias_

(1) Short alias

and

(2) You don't have to type,

I know it's rare, but over time, you do it hundreds of times, and you tend to use aliases whenever possible

#2 building

I think there is an unwritten rule (similar to a convention) that says that using "aliases" is only used to register method name aliases, which means that if you want to provide code users with a method with multiple names:

class Engine
  def start
    #code goes here
  end
  alias run start
end

If you need to extend the code, use the ruby meta option.

class Engine
  def start
    puts "start me"
  end
end

Engine.new.start() # => start me

Engine.class_eval do
  unless method_defined?(:run)
    alias_method :run, :start
    define_method(:start) do
      puts "'before' extension"
      run()
      puts "'after' extension"
    end
  end
end

Engine.new.start
# => 'before' extension
# => start me
# => 'after' extension

Engine.new.run # => start me

#3 building

A year after the question was asked, there was a new article on the subject:

http://erniemiller.org/2014/10/23/in-defense-of-alias/

It seems that "there are many people, there are many brains". Starting from the previous article, the author encourages the use of alias_method, while in the latter article, it is recommended to use alias.

However, there is a common overview of these methods in the above posts and answers:

• Use alias when you want to restrict alias to a defined scope
• Use alias method to allow inherited classes to access it

#4 building

In addition to grammar, the main differences are scope:

# scoping with alias_method
class User

  def full_name
    puts "Johnnie Walker"
  end

  def self.add_rename
    alias_method :name, :full_name
  end

end

class Developer < User
  def full_name
    puts "Geeky geek"
  end
  add_rename
end

Developer.new.name #=> 'Geeky geek'

In the above case, the method "name" selects the method "full" name "defined in the" Developer "class. Now let's try using alias.

class User

  def full_name
    puts "Johnnie Walker"
  end

  def self.add_rename
    alias name full_name
  end
end

class Developer < User
  def full_name
    puts "Geeky geek"
  end
  add_rename
end

Developer.new.name #=> 'Johnnie Walker'

When using aliases, method 'name' will not be able to select method 'full'name' defined in Developer.

This is because alias is a keyword and is within the lexical scope. This means that it treats self as a value of self when reading the source code. Instead, alias_method treats self as a value determined at run time.

Source: http : //blog.bigbinary.com/2012/01/08/alias-vs-alias-method.html

#5 building

If necessary, you can redefine alias method. (defined in the Module class.)

The behavior of alias varies according to its scope, sometimes it may be unpredictable.

Conclusion: using alias? Method gives you more flexibility.

Usage:

def foo
  "foo"
end

alias_method :baz, :foo