Comment by t-writescode

To add, the above code is a pretty near approximation of the literal code inside the devise codebase, which is a very standard Ruby auth system.

See here:

https://github.com/heartcombo/devise/blob/main/lib/devise/co...

        def self.define_helpers(mapping) #:nodoc:
        mapping = mapping.name

        class_eval <<-METHODS, __FILE__, __LINE__ + 1
          def authenticate_#{mapping}!(opts = {})

That code is *literally* calling class_eval with a multi-line string parameter, where it inlines the helper name (like admin, user, whatever), to grow the class at runtime.

It hurts my soul.