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Bug #20392

closed

Delegate super calls with a block

Added by tenderlovemaking (Aaron Patterson) 8 months ago. Updated 8 months ago.

Status:
Closed
Assignee:
-
Target version:
-
ruby -v:
ruby 3.4.0dev (2024-03-15T18:08:39Z master e3a82d79fd) [arm64-darwin23]
Backport:
3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN
[ruby-core:117313]

Description

I'm seeing strange behavior with calls to super when combined with ... and a block. I'm not sure if this is expected behavior or not, so I'm filing this ticket.

Using delegate ... with an explicit block will cause an error:

# Example 1
def foo ...
  yield
end

def bar ...
  foo(...) { } # test.rb: test.rb:6: both block arg and actual block given (SyntaxError)
end

However, calling super and passing a block works:

# Example 2
class A
  def foo
    yield(3)
  end
end

class B < A
  def foo(...)
    super do |x|
      yield(2 + x)
    end
  end
end

p B.new.foo { |x| x } # 5

In the above code, I imagine the bare super to basically be equivalent of super(...) since I defined the method foo as foo(...).

However, if I explicitly pass ... to super, there is no syntax error, just the block I provided is ignored:

# Example 3
class A
  def foo
    yield(3)
  end
end

class B < A
  def foo(...)
    super(...) do |x|
      raise "should I be called?"
    end
  end
end

p B.new.foo { |x| x } # 3

I'd expect Example 3 to raise an exception like Example 1. Additionally, I think the behavior in Example 2 is odd, but zsupers are "special" so I can understand if it is intended behavior.

Is Example 3 intended behavior? If not, how should it behave?

Thanks.

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