From: Logan Capaldo <logancapaldo@...>
Date: 2007-08-14T19:10:38+09:00
Subject: Re: what is "dynamic constant assignment"

------=_Part_34893_13803783.1187086240852
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline

On 8/14/07, Stefano Crocco <stefano.crocco@alice.it> wrote:
>
> Alle marted=EC 14 agosto 2007, Nikos Kanellopoulos ha scritto:
> > 2007/8/14, sean liu <seanliugm@gmail.com>:
> > > hi, all
> > >
> > > today i defined a class like this:
> > > class C
> > >   AB =3D 10
> > >   def self.set(value)
> > >      AB =3D value
> > >   end
> > > end
> > > then i got this error: SyntaxError: compile error (irb):10: dynamic
> > > constant assignment.
> > > Constants can be changed after initialization, but what does this
> error
> > > mean?
> > > Any explanations will be appreciated.
> >
> > Variable AB is a contant, because it starts with a capital letter.
> > You can only assign a contant value (or expression) to it, once.
>
> That's not true. You can assign a value to a constant more than once, eve=
n
> if
> ruby will issue a warning:
>
> irb: 001> A =3D 1
> 1
> irb: 002> A =3D 2
> (irb):2: warning: already initialized constant A
> 2
>
> I guess that the 'dynamic constant assignment' means that you can assing
> to a
> constant in a method.


And the work around is
def self.set(value)
  const_set("AB". value)
end

Although it might make more sense to do

@AB =3D 10
def self.AB
  @AB
end

def self.AB=3D(value)
  @AB =3D value
end



Stefano
>
>
>
>

------=_Part_34893_13803783.1187086240852--