21天 Ruby-------- symbol

Test1.rb

print "1: "
puts "name".object_id
print "1: "
puts "name".object_id
print "1: "
puts "name".object_id

print "2: "
puts :name.object_id
print "2: "
puts :name.object_id
print "2: "
puts :name.object_id

print "3: "
puts 123456.object_id
print "3: "
puts 123456.object_id
print "3: "
puts 123456.object_id

# output
#1: 21719110
#1: 21719080
#1: 21719050 
#  "name".object --> 对象的Id
#2: 34258
#2: 34258
#2: 34258
#  :name.object_id  -->  对象的值的Id
#3: 246913
#3: 246913
#3: 246913

==>
1.对象的相同的字符串，他们的对象不同， 但是 属性的值的Id相同
像java里面的Long与long区别
3.数字型的 对象Id相等

Test2.rb

class A
  attr_accessor :name
end

a = A.new
print "a.name = "
puts a.name

a.name = "Lily"
print "a.name = "
puts a.name

class B
  def name
    @name
  end
  
  def name=(name)
    @name = name
  end
end

b = B.new
print "b.name = "
puts b.name

b.name = "Lily"
print "b.name = "
puts b.name

# output
#a.name = nil
#a.name = Lily
#b.name = nil
#b.name = Lily

==>
1. 对象属性没有值的时候，为nil， 感觉是"Null Object"
2. ttr_accessor :name 的效果 当然于class B里面的

Test3.rb

class Symbol
  def to_proc
    proc {|obj, *args| obj.send(self, *args)}
  end
end

words = %w(abc bcd cde def efg)
list = words.map(&:capitalize)
print "1: "
puts list.inspect

list2 = words.map {|w| w.send(:capitalize)}
print "2: "
puts list2.inspect

==>
1. ruby中的神奇函数inspect，
2. capitalize顾名思义
#TODO