Ruby Language Dynamic Evaluation Instance evaluation
Example
The instance_eval method is available on all objects. It evaluates code in the context of the receiver:
object = Object.new
object.instance_eval do
@variable = :value
end
object.instance_variable_get :@variable # => :value
instance_eval sets self to object for the duration of the code block:
object.instance_eval { self == object } # => true
The receiver is also passed to the block as its only argument:
object.instance_eval { |argument| argument == object } # => true
The instance_exec method differs in this regard: it passes its arguments to the block instead.
object.instance_exec :@variable do |name|
instance_variable_get name # => :value
end
