Instance variable not avaliable in instance method call

Question

Given the situation below, why can't I access my @inst variable in the Prawn block?

calling: PdfGen.new('inst').build

class PdfGen
 @class = "class"

  def initialize(inst)
   @inst = inst
  end

  def build
    @inst  #=> 'inst'
    Prawn::Document.generate() do
      @inst  #=> nil
      @class #=> 'class'
    end
  end

end

Please include what you have tried, what you expect to happen, and what actually happens. As it is, if I copy and paste your code and run PdfGen.new('foo').build it raises an exception because you have not formatted your generate call properly. — anothermh
– anothermh, Commented Oct 31, 2017 at 18:44

zinovyev · Accepted Answer · 2017-10-31 18:53:26Z

2

It seems like Prawn::Document.generate() evaluates code block in it's own scope (e.g. via #instance_eval method), different from your object's scope.

You can prove it by printing puts class in this block. This will give you a picture of what's going on there)

answered Oct 31, 2017 at 18:53

zinovyev

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1 Comment

apt Over a year ago

Hi that is exactly it. ` def initialize(&block)` if block block.arity < 1 ? instance_eval(&block) : block[self] end end

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