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I can see ivar term mentioned many times here https://github.com/rails/rails/issues/18950#issuecomment-77924771 but can't find straight forward explanation what is the iVar.
What is it and can this term be used outside controller context?
649
An opaque type that represents an instance variable. iOS 4.0+ iPadOS 4.0+ macOS 10.5+ tvOS 9.0+ watchOS 2.0+
A variable set in Rails controller starting with @ sign are called instance variables. The specialty of instance variables is that they're available in our Rails views. We don't need to pass them explicitly to our Rails views. That's why in the index.
The Rails controller is the logical center of your application. It coordinates the interaction between the user, the views, and the model. The controller is also a home to a number of important ancillary services. It is responsible for routing external requests to internal actions.
Used declare variables within a class. There are two main types: class variables, which have the same value across all class instances (i.e. static variables), and instance variables, which have different values for each object instance.
ivar stands for instance variable. An instance variable is bound to an object of a given class and, in rails, is mainly used in controllers and views.
This is from the github issue you have posted: 'iVars essentially serve as the recommended "API" between controllers and views.'
For example in your controller:
def new
@post_ivar = Post.new
end
You can now use this 'ivar' in your view for your new action, i.e. new.haml:
= form_for @post_ivar do |f|
= f.text_field :headline
-# ...
answered Nov 15 '22 11:11
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