CODEWITHSUNDEEP
ruby-on-rails
Hommer Smith
Hommer Smith

Reputation: 27862

Calling private method in ApplicationController?

I am confused on how this library works:

The ApplicationController has a private method called selected_account() as you can see here: ApplicationController

Then, from another Controller which is a child from ApplicationController, we do an action that does this:

 def index()
    @selected_account = selected_account
    graph = get_accounts_graph()
    @accounts = Account.get_accounts_map(graph)
  end

How can we do that? Isn't it out of scope?

Upvotes: 1

Views: 2512

Answers (3)

usha
usha

Reputation: 29369

This will be confusing for those who come from java or c# world. But here is a decent explanation

In Ruby, the inheritance hierarchy or the package/module don't really enter into the equation, it is rather all about which object is the receiver of a particular method call. When a method is declared private in Ruby, it means this method can never be called with an explicit receiver. Any time we're able to call a private method with an implicit receiver it will always succeed. This means we can call a private method from within a class it is declared in as well as all subclasses of this class

Upvotes: 2

Stefan Kanev
Stefan Kanev

Reputation: 3040

It might be confusing at first, but in Ruby private does not mean what it means in Java/C++. Ancestors can call private methods just fine.

What private actually means is that you cannot call the method with an explicit target. That is, if foo is private, you can call it with foo(), but not with self.foo() or obj.foo(). That way you can call private methods only on yourself.

Furthermore, Ruby has protected. The semantics are again different from Java/C++ – protected methods can only be called from instances of the same class. It is rarely used.

Upvotes: 2

cpjolicoeur
cpjolicoeur

Reputation: 13106

The child controller inherits from ApplicationController so it can call internal private methods on itself without issue. There is no scoping problem. The subclass inherits all the public/private/protected methods of its super class.

Upvotes: 0

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