Bug #19795
Updated by francktrouillez (Franck Trouillez) 10 months ago
### 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:
``` ruby
# attr_accessor_nil.rb
class A
attr_accessor :a
def initialize
@a = 0 1
end
def my_method
puts "a is '#{a.inspect}' of class '#{a.class}'"
a += 1 if a.positive? # use an integer method
end
end
instance = A.new
instance.my_method
# output:
#
# a is '0' '1' of class 'Integer'
# attr_accessor_nil.rb:12:in `my_method': undefined method `+' `positive?' for nil:NilClass (NoMethodError)
#
# a += 1 if a.positive? # use an integer method
# ^ ^^^^^^^^^^
# 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:
```ruby
# 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' '1' of class 'Integer'
```
This snippet runs just fine, and no error is raised.
### System configuration
Ruby version : 3.2.2