Redefine a class with same name

Ruby
1

Is there any way to to remove the definition of a class so I can reuse
its
name? Like below I’d like to reuse the name ‘A’ but since it’s already
defined with a different superclass I get a ‘TypeError: superclass
mismatch
for class A’.

class X
end
class Y
end

class A < X
end

==> Here I’d like to remove A’s definition so I can:

class A < Y
end

==> without getting a: ‘TypeError: superclass mismatch for class A’

Thanks,
Martin

2

“M” == Martin B. [email protected] writes:

M> Is there any way to to remove the definition of a class so I can
reuse its
M> name? Like below I’d like to reuse the name ‘A’ but since it’s
already
M> defined with a different superclass I get a ‘TypeError: superclass
mismatch
M> for class A’.

Just remove the constant

M> class A < X
M> end

Object.send(:remove_const, :A)

M> class A < Y
M> end

Guy Decoux

3

Excellent! That’s fine for me. I only have the case for a web framework
of
mine when using with fastcgi as different calls might use same class
names
which I can unregister now.

Thanks,
martin

4

On 3/9/08, ts [email protected] wrote:

M> end

Object.send(:remove_const, :A)

M> class A < Y
M> end

Keep in mind though, that this only removes the binding between the
constant and the class, it doesn’t actually allow you to change the
old class, and any existing instances will still be instances of the
old class not the new one:

k$ irb
irb(main):001:0> class A
irb(main):002:1> def foo
irb(main):003:2> end
irb(main):004:1> end
=> nil
irb(main):005:0> a = A.new
=> #<A:0x6e578>
irb(main):006:0> a.foo
=> nil
irb(main):007:0> Object.send(:remove_const, :A)
=> A
irb(main):008:0> a.foo
=> nil
irb(main):009:0> a.class
=> A
irb(main):010:0> A
NameError: uninitialized constant A
from (irb):10
irb(main):011:0> class A
irb(main):012:1> def bar
irb(main):013:2> end
irb(main):014:1> end
=> nil
irb(main):015:0> a.bar
NoMethodError: undefined method `bar’ for #<A:0x6e578>
from (irb):15
irb(main):016:0>

–
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/