rspec users - Sep 2010 - variable strange change

class User
  has_many :mads

  def mad
    Mad.find_by_user_id(id)
  end
end

class God
  belongs_to :mad
  belongs_to :user
  belongs_to :sender, :class_name => "User", :foreign_key =>
"sender_id"

  def strange_change!
    God.transaction do
      puts mad.nil?    #the first time put is false
      if mad.nil?
        puts ''some thing exctue here''           #no puts
anything
        mad = you.mad
      end
      puts mad.nil?    #the second time put is true
    end
  end
end

why the mad will become nil?
-- 
Posted via http://www.ruby-forum.com/.

On Wed, Sep 15, 2010 at 3:19 AM, Zhenning Guan <lists at ruby-forum.com>
wrote:
> class User
> ?has_many :mads
>
> ?def mad
> ? ?Mad.find_by_user_id(id)
> ?end
> end
>
> class God
> ?belongs_to :mad
> ?belongs_to :user
> ?belongs_to :sender, :class_name => "User", :foreign_key =>
"sender_id"
>
> ?def strange_change!
> ? ?God.transaction do
> ? ? ?puts mad.nil? ? ?#the first time put is false
> ? ? ?if mad.nil?
> ? ? ? ?puts ''some thing exctue here'' ? ? ? ? ? #no puts
anything
> ? ? ? ?mad = you.mad
> ? ? ?end
> ? ? ?puts mad.nil? ? ?#the second time put is true
> ? ?end
> ?end
> end
>
> why the mad will become nil?
Seems like a Rails question, not an RSpec question. Please post Rails
questions to http://groups.google.com/group/rubyonrails-talk.

Cheers,
David

Typical Ruby gotcha:

    God.transaction do
      puts mad.nil?    # mad is instance method of God and returns
BelongsToAssociation here
      if mad.nil?
        puts ''some thing exctue here''
        mad = you.mad # Ruby sees mad local variable definition
      end
      puts mad.nil?    # mad is unitialized local variable set to nil
    end

On Wed, Sep 15, 2010 at 5:22 PM, David Chelimsky <dchelimsky at gmail.com>
wrote:
> On Wed, Sep 15, 2010 at 3:19 AM, Zhenning Guan <lists at
ruby-forum.com> wrote:
>> class User
>> ?has_many :mads
>>
>> ?def mad
>> ? ?Mad.find_by_user_id(id)
>> ?end
>> end
>>
>> class God
>> ?belongs_to :mad
>> ?belongs_to :user
>> ?belongs_to :sender, :class_name => "User", :foreign_key
=> "sender_id"
>>
>> ?def strange_change!
>> ? ?God.transaction do
>> ? ? ?puts mad.nil? ? ?#the first time put is false
>> ? ? ?if mad.nil?
>> ? ? ? ?puts ''some thing exctue here'' ? ? ? ? ? #no
puts anything
>> ? ? ? ?mad = you.mad
>> ? ? ?end
>> ? ? ?puts mad.nil? ? ?#the second time put is true
>> ? ?end
>> ?end
>> end
>>
>> why the mad will become nil?
>
> Seems like a Rails question, not an RSpec question. Please post Rails
> questions to http://groups.google.com/group/rubyonrails-talk.
>
> Cheers,
> David
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