Redefine a Class?

ruby-talk
1

Currently this raises: superclass mismatch for class Soda (TypeError)
How can I redefine a class?
As a class is an object, if I remove all of it's methods, attr & @'s
could it be GC'd? (:wink:

···

#-----------------------------------------
class Soda
def initialize
@brand = "SweetenedSugar" end

def retrieve_brand
return @brand end end

class Soda < String
end
#-----------------------------------------

--
MarkT

2

Mark T wrote:

Currently this raises: superclass mismatch for class Soda (TypeError)
How can I redefine a class?
As a class is an object, if I remove all of it's methods, attr & @'s
could it be GC'd? (:wink:
#-----------------------------------------
class Soda
def initialize
@brand = "SweetenedSugar" end

def retrieve_brand
return @brand end end

class Soda < String
end
#-----------------------------------------

What are your trying to do? You want to extend Stirng class? I ask,
because at the moment I see that you are trying to define Soda class
twice. First definition is a standalone class, and the second by
extending String class.

···

--
Posted via http://www.ruby-forum.com/\.

3

Hi Marcin,
The String class is used as an example Class.
Could be anything.
Issue is in trying to (delete)/redefine a class.

What are your trying to do? You want to extend String class? I ask,

MarkT

4

Mark T wrote:

Hi Marcin,
The String class is used as an example Class.
Could be anything.
Issue is in trying to (delete)/redefine a class.

What are your trying to do? You want to extend String class? I ask,

MarkT

You can open existing class, and redefine methods. For example

#defined Soda class
class Soda
  def initialize
    @brand = "SweetenedSugar"

  end

  def retrieve_brand
    return @brand
  end
end

puts Soda.new.retrieve_brand
#this will return "SweetenedSugar"

#now, for example, you can open this class and redefine retrieve_brand
method
class Soda
  def retrieve_brand
    return @brand.upcase
  end
end

puts Soda.new.retrieve_brand
#this will return "SWEETENEDSUGAR"

Hope this is what you want?

···

--
Posted via http://www.ruby-forum.com/\.

5

I'm looking for something... kinda 'destructive'....

class Soda
def initialize
@brand = "SweetenedSugar" end

def retrieve_brand
return @brand end end

Soda.removeClassAndMethods # yet to be (found) or
implemented method.....

irb(main):001:0> Soda.retrieve_brand
NameError: uninitialized constant Soda
        from (irb):1
#---------------------------- ^ yep, this error is what I'm looking for.....

MarkT

6

Mark T wrote:

I'm looking for something... kinda 'destructive'....

class Soda
def initialize
@brand = "SweetenedSugar" end

def retrieve_brand
return @brand end end

Soda.removeClassAndMethods # yet to be (found) or
implemented method.....

irb(main):001:0> Soda.retrieve_brand
NameError: uninitialized constant Soda
        from (irb):1
#---------------------------- ^ yep, this error is what I'm looking
for.....

MarkT

You can remove a method as follows:

class Soda
  remove_method :retrieve_brand
end

···

--
Posted via http://www.ruby-forum.com/\.

7

IIUC you want

Soda = Class::new do
  def a; 42 end
end

Soda = Class::new( String ) do
# Completely new class here, the old can indeed be GCed
end

You will get a const redefined warning, but if that hurts there are
solutions, just probably out of topic here.

HTH
R.

···

On Tue, May 25, 2010 at 9:18 AM, Mark T <paradisaeidae@gmail.com> wrote:

--
The best way to predict the future is to invent it.
-- Alan Kay

8

I'm looking for something... kinda 'destructive'....

class Soda
def initialize
@brand = "SweetenedSugar" end

def retrieve_brand
return @brand end end

Soda.removeClassAndMethods # yet to be (found) or
implemented method.....

irb(main):001:0> Soda.retrieve_brand
NameError: uninitialized constant Soda
from (irb):1
#---------------------------- ^ yep, this error is what I'm looking for.....

irb(main):001:0> class Soda
irb(main):002:1> end
=> nil
irb(main):005:0> self.class.send(:remove_const,:Soda)
=> Soda
irb(main):006:0> Soda
NameError: uninitialized constant Soda
  from (irb):6
irb(main):007:0> class Soda < String
irb(main):008:1> end
=> nil

Jesus.

···

On Tue, May 25, 2010 at 9:18 AM, Mark T <paradisaeidae@gmail.com> wrote:
  from :0

9

Thanks all!!

MarkT

10

should that not rather be
   Object.send ....

R.

···

2010/5/25 Jesús Gabriel y Galán <jgabrielygalan@gmail.com>:

irb(main):005:0> self.class.send(:remove_const,:Soda)

11

Could very well be :-).
I just saw that remove_const was a method in Module and I thought:
self.class is a Module, so I'll use that.

Jesus.

···

On Tue, May 25, 2010 at 4:56 PM, Robert Dober <robert.dober@gmail.com> wrote:

2010/5/25 Jesús Gabriel y Galán <jgabrielygalan@gmail.com>:

irb(main):005:0> self.class.send(:remove_const,:Soda)

should that not rather be
Object.send ....

12

Where did I have my head? send remove_const to Object for top level
constants and for all other to their defining module object, of
course. Sorry got confused with irb output - that is waaay of a bad
excuse I know :wink:
Cheers
R.

···

2010/5/25 Jesús Gabriel y Galán <jgabrielygalan@gmail.com>:

Could very well be :-).
I just saw that remove_const was a method in Module and I thought:
self.class is a Module, so I'll use that.

--
The best way to predict the future is to invent it.
-- Alan Kay