Redefine a Class?

Ruby
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
#-----------------------------------------

2

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

3

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.

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?

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

7

On Tue, May 25, 2010 at 9:18 AM, Mark T [email protected] wrote:
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.

8

On Tue, May 25, 2010 at 9:18 AM, Mark T [email protected] wrote:

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
from :0
irb(main):007:0> class Soda < String
irb(main):008:1> end
=> nil

Jesus.

9

2010/5/25 Jesús Gabriel y Galán [email protected]:

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

should that not rather be
Object.send …

R.

10

On Tue, May 25, 2010 at 4:56 PM, Robert D. [email protected]
wrote:

2010/5/25 Jesús Gabriel y Galán [email protected]:

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

should that not rather be
Object.send …

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.

11

Thanks all!!

MarkT

12

2010/5/25 Jesús Gabriel y Galán [email protected]:

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.
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.