How do I convert a string to a class method?

Question

This is how to convert a string to a class in Rails/Ruby:

p = "Post" Kernel.const_get(p) eval(p) p.constantize 

But what if I am retrieving a method from an array/active record object like:

Post.description 

but it could be

Post.anything 

where anything is a string like anything = "description".

This is helpful since I want to refactor a very large class and reduce lines of code and repetition. How can I make it work?

Answer 1

Post.send(anything) 

Answer 2

While eval can be a useful tool for this sort of thing, and those from other backgrounds may take to using it as often as one might a can opener, it's actually dangerous to use so casually. Eval implies that anything can happen if you're not careful.

A safer method is this:

on_class = "Post" on_class.constantize.send("method_name") on_class.constantize.send("method_name", arg1) 

Object#send will call whatever method you want. You can send either a Symbol or a String and provided the method isn't private or protected, should work.