Alias and alias_method IN RUBY

Both alias and alias_method in Ruby can be renamed. The differences between them are as follows:

 

1. Alias is a keyword of Ruby, so it is alias: newname: oldname.

Alias_method is a method of the module class. Therefore, alias_method: newname, oldname, and a comma is used.

 

2. the alias parameter can be a function name or symbol, not a string.

The alias_method parameter can be a string or a symbol.

The following code:

 1 class Array 2   alias :f1 :first 3   alias f2 first 4   alias_method :f3,:first 5   alias_method "f4","first" 6 end 7 p [1,2,3].f1 8 p [1,2,3].f2 9 p [1,2,3].f310 p [1,2,3].f4

Output:

1
1
1
1

 

3. They are different in the following situations.

 1 class A 2    3   def method_1 4     p "this is method 1 in A" 5   end 6    7   def A.rename 8     alias :method_2 :method_1 9   end10 end11 12 class B < A13   def method_114     p "This is method 1 in B"15   end16   17   rename18 end19 20 B.new.method_221 22

23 class A24   25   def method_126     p "This is method 1 in A"27   end28   29   def A.rename30     alias_method :method_2,:method_131   end32 end33 34 class B < A35 36   def method_137     p "This is method 1 in B"38   end39   40   rename41 end42 B.new.method_2

The output is

"This is method 1 in"
"This is method 1 in B"

The result shows that for alias_method, The subclass method is called. If alias is used, the parent class method is called.

Alias and alias_method IN RUBY