From: Robert Klemme <shortcutter@...>
Date: 2010-02-12T17:59:10+09:00
Subject: Re: String to symbol

2010/2/12 Sergey Sheypak <serega.sheypak@gmail.com>:
> Hello, I'm working with yaml and objects.
> Please, see my model:
>
> #Base class for all models.
> class DataBean
>  #list allowed fields for model
>  def allowed_fields
>    []
>  end
>
>  def is_attr_allowed!(attr)

IMHO that method would rather be called ensure_attr_allowed - if you
call it is_... I would expect it to return a boolean.

>    raise(ValidationException, "Attribute with name [#{attr}] is not
> allowed for model #{self.class}.
>                                     Allowed fields are
> #{allowed_fields}", caller) unless allowed_fields.include?(attr)
>  end
>
>  def initialize(options)
>      options.each_pair { |attr_name , value|
>        is_attr_allowed!(attr_name)
>        self.class.send(:define_method, attr_name, Proc.new{value})
>      }
>  end

Are you sure this is what you want?  It seems you change the accessor
method for *all* instances to return the *same* value.  I don't think
this is a good idea.

> end
>
> class Dates < DataBean
>  def allowed_fields
>    [:start,  #project beginning
>     :end,    #project ending
>     :current] #last modification date "T", means current date
>  end
> end
>
> So I can use 'rails like intializers'
> Dates.new(:start=>Date.new, :end=>Dates.new+100)
>
> The problem is that I'm reading Dates class fields from yaml file.
>
> Dates:
>  class: Dates
>  fields_ordered: [start, current, end]
>
> And I pass String (read from yaml) as a hash key to initializer:
> Dates.new('start'=>Date.new)
>
> As I read, :symbols are constants, they are immutable and have int
> representation. These facts help to spend less memory and resources.
>
> Do I have any opportunity to pass Strings into my initializers?

Did you try it out with your code?  Was there an issue, if so, which one?

Kind regards

robert

-- 
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