CODEWITHSUNDEEP
rubyexception
Sathish
Sathish

Reputation: 1475

Could we rescue, raise and rescue the same error again using exception hierarchy syntax in ruby?

I would like the exceptions to be rescued, raised and rescued again using exception hierarchy syntax like the below snippet..

class InnerCustomError < StandardError
  def initialize(msg = "inner")
    super
  end
end

class OuterCustomError < StandardError
  def initialize(msg = "outer")
    super
  end
end

begin
  raise InnerCustomError
rescue InnerCustomError
  raise OuterCustomError
rescue OuterCustomError, StandardError => e
  e.message
end

but this raises ==> OuterCustomError (outer)

why is this behaviour? Instead I would like it to be rescued ..

I understand nested begin end blocks like below is used to achieve the same,

begin
  begin 
    raise InnerCustomError
  rescue InnerCustomError 
    raise OuterCustomError
  end
rescue OuterCustomError, StandardError => e
  e.message
end

also I understand there are performance impacts with this idea but I would like to understand how is the former interpreted?

Upvotes: 1

Views: 279

Answers (1)

Sergio Tulentsev
Sergio Tulentsev

Reputation: 230286

but this raises OuterCustomError. Why is this behaviour?

Because that's how this construct works. The first matching rescue is selected as a handler for the exception and the result of this handling will be the result of the begin/rescue. If the handler raises and you want to catch that new exception, you need to add another layer of begin/rescue, exactly like you show in the last snippet.

It is described in the documentation here.

Upvotes: 3

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