Delete from class

ruby-talk
1

Hi

I have found this tutorial http://juixe.com/techknow/index.php/2007/01/22/ruby-class-tutorial/
where there is the following class:

···

###
class Person
  attr_accessor :fname, :lname

  def initialize(fname, lname)
    @fname = fname
    @lname = lname
  end

  def to_s
    @lname + ", " + @fname
  end

  def self.find_by_fname(fname)
    found = nil
    ObjectSpace.each_object(Person) { |o|
    found.push(o) if o.fname == fname
    }
    found
  end
end
###

Is it possible to add a self.delete that will delete the entry found by the self.find_by_fname?

/Emil

2

Hi

I have found this tutorial Ruby Class Tutorial | Juixe Techknow
where there is the following class:

###
class Person
attr_accessor :fname, :lname

def initialize(fname, lname)
@fname = fname
@lname = lname
end

def to_s
@lname + ", " + @fname
end

def self.find_by_fname(fname)
found = nil
ObjectSpace.each_object(Person) { |o|
found.push(o) if o.fname == fname
}
found
end
end
###

That's an awful and inefficient way to do it. A proper implementation
would at least hold an Array or Hash with all Persons in some global
place instead of resorting to ObjectSpace. ObjectSpace is a tool for
rather special situations and finalization handling.

Is it possible to add a self.delete that will delete the entry found by the self.find_by_fname?

No. What would "deleting" mean here? There can be arbitrary many
references pointing to that instance found (including null, if GC has
not reclaimed an unreachable object):

~$ ruby19 -e 's="foo";id=s.object_id;s=nil;ObjectSpace.each_object(String){|st|
p st if st.object_id == id}'
"foo"

s is unreachable yet you see it through ObjectSpace.

Kind regards

robert

···

On Fri, Feb 17, 2012 at 10:46 AM, Emil Enemærke <eme@medical-insight.com> wrote:

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/