alias versus alias_method
Last week Ian and I were running into a problem with
alias_method. It turned out that we were passing the method
name to alias method as you would to alias, instead of passing a string
or a symbol of the method name. Here is the correct usage of alias and
Here is the blog post that pointed out our error. It is in Spanish, so for the first time ever all that time I spent learning Spanish helped me as a programmer ;).
For the benefit of English speakers I decided to translate the blog post. Here is the translated text:
alias and alias_method do the same thing: copy a method and assign it a different name.
That piqued my curiosity to know the difference between alias and alias_method. It turns out that they are the same, except that:
- alias is a reserved keyword in Ruby
- alias takes the method identifiers as parameters, without the need to use symbols or strings (for example in “def method_name”, method_name is an identifier and not a string or a symbol) This behavior can be pretty confusing when you’re starting out.
- alias_method is a method of the class Module
- alias_method takes its parameters separated by comma, just like any other method.
The consequences are simple:
- alias_method can be redefined, and alias can’t.
- alias can be used incorrectly (outside the context of method definitions)
By being a method of Module, alias_method makes it easier to use it correctly: in the context of method definition of a class or module.
Conclusion: In the majority of cases, alias_method is what you need.
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