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Bug #19795
closedattr_accessor leading to nil values for re-assignment
Status:
Closed
Assignee:
-
Target version:
-
ruby -v:
ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x86_64-linux]
Description
Steps to reproduce:¶
- Create a class with an
attr_accessor
for an instance variable - Create an instance method that reassign this variable using the current value stored in the variable
- Show that the variable is set to nil during the evaluation
Code snippet:
# attr_accessor_nil.rb
class A
attr_accessor :a
def initialize
@a = 0
end
def my_method
puts "a is '#{a.inspect}' of class '#{a.class}'"
a += 1
end
end
instance = A.new
instance.my_method
# output:
#
# a is '0' of class 'Integer'
# attr_accessor_nil.rb:12:in `my_method': undefined method `+' for nil:NilClass (NoMethodError)
#
# a += 1
# ^
# from attr_accessor_nil.rb:17:in `<main>'
Expected behavior¶
a += 1
should lead to a
being equal to 1
at the end of the assignment, because a
was storing 0
previously, as shown by the puts
. Am I being wrong expecting this result?
Actual behavior¶
a += 1
raises an error about a
being nil
in the evaluation.
Further investigation¶
I checked if it was coming from the "instance variable", or about the "attr_accessor" by running the following snippet:
Code snippet:
# attr_accessor_nil.rb
class A
attr_accessor :a
def initialize
@a = 0
end
def my_method
puts "a is '#{a.inspect}' of class '#{a.class}'"
@a += 1 # use the instance variable directly, instead of the accessor
end
end
instance = A.new
instance.my_method
# output:
#
# a is '0' of class 'Integer'
This snippet runs just fine, and no error is raised.
System configuration¶
Ruby version : 3.2.2
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