From: Eero Saynatkari <ruby-ml@...>
Date: 2005-12-29T14:51:02+09:00
Subject: Re: Locking classes?

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(Sorry if this is a duplicate.)

On 2005.12.29 14:04, Gerardo Santana G�mez Garrido
<gerardo.santana@gmail.com> wrote:
> 2005/12/28, Max Eskin <kurtkilgor@yahoo.com>:
> > Hi,
> > I am just starting to use Ruby. I'm wondering, once a class has been
> > declared, is there any way to lock it to prevent further methods from
> > being defined? In other words is there a way to make Ruby act like a
> > static language for some classes?
> 
> Use Module#freeze
> 
> class A
>   def self.f(a)
>     a + 1
>   end
> end
> 
> puts A.f(1)   # => 2
> 
> A.freeze
> 
> #=> runtime error: "can't modify frozen object (TypeError)"
> class A
>   def self.f(a)
>     a - 1
>   end
> end
> 
> puts A.f(1)

One can still A.dup, but I think this is a reasonable way :)

> Gerardo Santana


E
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