See below, what's the proper way of checking for initialized
class-variables ?
Cheers
John
--
irb(main):031:0> @nosuchvar.nil?
=> true
irb(main):032:0> @@nosuchvar.nil?
NameError: uninitialized class variable @@nosuchvar in Object
from (irb):32
irb(main):033:0>
--
Posted via http://www.ruby-forum.com/.
Hi --
On Mon, 1 Sep 2008, John Pritchard-williams wrote:
See below, what's the proper way of checking for initialized
class-variables ?Cheers
John
--
irb(main):031:0> @nosuchvar.nil?
=> true
irb(main):032:0> @@nosuchvar.nil?
NameError: uninitialized class variable @@nosuchvar in Object
from (irb):32
irb(main):033:0>
defined?(@@nosuchvar)
David
--
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John Pritchard-williams wrote:
See below, what's the proper way of checking for initialized
class-variables ?
[...]
irb(main):031:0> @nosuchvar.nil?
=> true
That doesn't check whether @nosuchvar was initialized. Look:
defined?(@var)
=> nil
@var.nil?
=> true
@var = nil # @var is now initialized
=> nil
@var.nil?
=> true
defined?(@var)
=> "instance-variable"
HTH,
Sebastian
--
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irb(main):031:0> @nosuchvar.nil?
=> true
irb(main):032:0> @@nosuchvar.nil?
NameError: uninitialized class variable @@nosuchvar in Object
from (irb):32
irb(main):033:0>
Well, to query about class variables/methods, I would prefer to use
class methods.
use self.class to get the class object of current instance, then query
the class variables of this class using class_variable_defined? method.
irb(main):026:0> self.class.class_variable_defined? :@@nosuchvar
=> false
--
Posted via http://www.ruby-forum.com/\.
Thanks !
David A. Black wrote:
//defined?(@@nosuchvar)
--
Posted via http://www.ruby-forum.com/.
You forgot the disclaimer that class variables are fragile and should
be avoided. 
Kind regards
robert
2008/9/1 David A. Black <dblack@rubypal.com>:
On Mon, 1 Sep 2008, John Pritchard-williams wrote:
See below, what's the proper way of checking for initialized
class-variables ?
--
irb(main):031:0> @nosuchvar.nil?
=> true
irb(main):032:0> @@nosuchvar.nil?
NameError: uninitialized class variable @@nosuchvar in Object
from (irb):32
irb(main):033:0>defined?(@@nosuchvar)
--
use.inject do |as, often| as.you_can - without end
//
You forgot the disclaimer that class variables are fragile and should
be avoided. 
//
Nah, I'll check each one with:
fragile?(@@var)
(that's just a bad joke)...but seriously : 'fragile' in implementation ?
or 'fragile' from a high-level/idealistic point of view ?
--
Posted via http://www.ruby-forum.com/.