CODEWITHSUNDEEP
ruby-on-railsruby
Aditya M P
Aditya M P

Reputation: 5347

How can this lambda be rewritten with a guard clause?

I'm using the following lambda, gathered from the README of Resque::Mailer (https://github.com/zapnap/resque_mailer):

  Resque::Mailer.error_handler = lambda { |mailer, _message, error, action, args|
    # Necessary to re-enqueue jobs that receive the SIGTERM signal
    if error.is_a?(Resque::TermException)
      Resque.enqueue(mailer, action, *args)
    else
      raise error
    end
  }

Unfortunately, rubocop enabled on the codebase, complains about the if..else nature of the method, with the error: Use a guard clause instead of wrapping the code inside a conditional expression.

I tried setting up an unless here, but so far, the raise error would be executed no matter which order I set it up. What's the right way to use a guard clause here?

To wit, the reason I ask this is, the following example seems to indicate that if I do the obvious thing with unless, the error will always be raised. Am I understanding this wrong?

Development [10] (main)> class Foo
Development [10] (main)*   def bar
Development [10] (main)*     puts "Outside unless getting exec" unless 1 == 2
Development [10] (main)*     puts "After unless getting exec"
Development [10] (main)*   end  
Development [10] (main)* end  
:bar
Development [11] (main)> Foo.new.bar
Outside unless getting exec
After unless getting exec
nil

Upvotes: 0

Views: 223

Answers (1)

eugen
eugen

Reputation: 9226

Transforming the condition into an unless should work, and satisfy rubocop:

 Resque::Mailer.error_handler = lambda { |mailer, _message, error, action, args|
    # Necessary to re-enqueue jobs that receive the SIGTERM signal
    raise error unless error.is_a?(Resque::TermException)
    Resque.enqueue(mailer, action, *args)
  }

Upvotes: 1

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