Why?
irb(main):012:0> a = 5
=> 5
irb(main):013:0> a.class
=> Fixnum
irb(main):014:0> a.methods.include?("dup")
=> true
irb(main):015:0> a.methods.include?("clone")
=> true
irb(main):016:0> a.dup
TypeError: can't dup Fixnum
from (irb):16:in `dup'
from (irb):16
from :0
irb(main):017:0> a.clone
TypeError: can't clone Fixnum
from (irb):17:in `clone'
from (irb):17
from :0
irb(main):018:0>
Because Fixnum's , like some other things like Symbols, nil, true,
false are immediate valued objects, there is only one instance of 1
just like there is only one instance of true, nil, or :abc. Since dup
and clone are defined to create a new object like the original, they
can't work on these objects.
Now as to why Fixnum has a dup method. That's just an implementation
choice. It is really getting it from the Kernel module. The
implementation checks the receiver and if it's an immediate object (or
what the implementation code calls a special constant, it throws that
exception.
On 3/1/07, Raj Sahae <rajsahae@gmail.com> wrote:
Why?
irb(main):012:0> a = 5
=> 5
irb(main):013:0> a.class
=> Fixnum
irb(main):014:0> a.methods.include?("dup")
=> true
irb(main):015:0> a.methods.include?("clone")
=> true
irb(main):016:0> a.dup
TypeError: can't dup Fixnum
from (irb):16:in `dup'
from (irb):16
from :0
irb(main):017:0> a.clone
TypeError: can't clone Fixnum
from (irb):17:in `clone'
from (irb):17
from :0
irb(main):018:0>
--
Rick DeNatale
My blog on Ruby
http://talklikeaduck.denhaven2.com/
Read this (long) thread.
Gary Wright
On Mar 1, 2007, at 4:56 PM, Raj Sahae wrote:
Why?
rb(main):016:0> a.dup
TypeError: can't dup Fixnum
from (irb):16:in `dup'
from (irb):16
from :0
Actually, I realized I mispoke slightly as soon as I sent this. These
are all what the implementation calls special constants which means
that there is a unique instance for a given value. Some of them like
SmallIntegers, nil, true, and false are allso immediate value objects
in that the value of a reference to one of these objects encodes the
value directly rather than acting as a pointer to ram which contains
the actual object.
On 3/1/07, Rick DeNatale <rick.denatale@gmail.com> wrote:
Because Fixnum's , like some other things like Symbols, nil, true,
false are immediate valued objects, t
--
Rick DeNatale
My blog on Ruby
http://talklikeaduck.denhaven2.com/
Sorry about that. Not sure why the link didn't show up:
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/239426
Gary Wright
On Mar 1, 2007, at 5:30 PM, Gary Wright wrote:
On Mar 1, 2007, at 4:56 PM, Raj Sahae wrote:
Why?
rb(main):016:0> a.dup
TypeError: can't dup Fixnum
from (irb):16:in `dup'
from (irb):16
from :0Read this (long) thread.