Style/RedundantBegin should detect redundant begin around memoization

[deivid-rodriguez]

Is your feature request related to a problem? Please describe.

I'd like rubocop to be able to detect redundant begin/end blocks around memoization, like here: 3b48d8b.

Describe the solution you'd like

I think it would fit nicely inside the existing Style/RedundantBegin cop.

Describe alternatives you've considered

A separate cop if excluding this case was intentional, I guess.

[koic]

Good catch! I think it can enhance Style/RedundantBegin cop.

[deivid-rodriguez]

Thanks!!

[koic]

@deivid-rodriguez You are welcome! 😄

[tas50]

Thanks @deivid-rodriguez and @koic chef/chef#11220

[Drenmi]

Would have been nice to have a configuration option, as we deliberately use this style for complex memoization expressions to avoid the indent-mega-blocks. 😬

[deivid-rodriguez]

@Drenmi Can you show an example of how this fix complicates indentation, if that's what you mean by indent-mega-blocks? Isn't

def foo
  @foo ||= begin
    mega_block do
      # ...      
      # a lot of code
      # ...
    end
  end
end 

equivalent to

def foo
  @foo ||=
    mega_block do
      # ...
      # a lot of code
      # ...
    end
end 

in terms of indentation? Or does it violate another common style rule?

[Drenmi]

The auto-correction with our current settings leaves:

def something
  @something ||= mega_block do
                   # ...
                 end
end

after removing begin and applying other rules. Another small point that caused confusion/mistakes in the past is the mismatched end when not using begin.

[deivid-rodriguez]

Ah I see. Yeah, I've been there. I don't like this mega-indented blocks and I do recall having to change the code manually to the alternative I mentioned since rubocop auto-correct prefers the other style. I don't get the problem with mismatched end though, where is the mismatch?

[alexventuraio]

Kind of the same issue from @Drenmi here:

# before
def decorator
  @decorator ||= begin
    case reminder.remindable_type
    when 'EmailSchedule'
      Notifier::EmailScheduleDecorator.new(reminder)
    when 'ReportScheduled'
      Notifier::ReportScheduledDecorator.new(reminder)
    else
      raise 'Unsupported type of Notifie'
    end
  end
end

# after
def decorator
  @decorator ||= case reminder.remindable_type
                  when 'EmailSchedule'
                    Notifier::EmailScheduleDecorator.new(reminder)
                  when 'ReportScheduled'
                    Notifier::ReportScheduledDecorator.new(reminder)
                  else
                    raise 'Unsupported type of Notifier'
                  end
end