Where to place and initialize application params

In general, environment.rb *is* the place where you should perform
configuration. There's even a comment at the bottom of the file to
that effect :slight_smile:

You need to consider what it is that you're actually configuring. If
it's some string which acts as the application title, you could place
this in a constant:

[ environment.rb, at the end ]

  ApplicationName = "I Caught You A Delicious Bass"

and then reference this constant somewhere else. In your example,
because 'application_name' doesn't start with a capital letter, Ruby
assumes that it is a local variable and it is almost certainly lost
within the scope of your ApplicationController (the class defined in
application.rb).

In a nutshell, use constants if you want to set some value that needs
to persist in a different part of Rails. You could even define these
within a module to keep the top-level namespace clear.