From: "David A. Black" <dblack@...>
Date: 2008-04-26T06:20:22+09:00
Subject: Re: undefined local variable

Hi --

On Sat, 26 Apr 2008, Johan Eriksson wrote:

> Hi --
>
> David A. Black wrote:
>> Hi --
>> 
>> On Sat, 26 Apr 2008, Johan Eriksson wrote:
>> 
>>> Chris Hulan wrote:
>>>> On Apr 25, 11:16 am, Johan Eriksson <jo...@johaneriksson.se> wrote:
>>>>> Hi!
>>>>> 
>>>>> I have some troubles with this.
>>>>>
>>>>>            obj_as_list.each do |att|
>>>>>              if att[1].is_a?(String)
>>>>>                att[1] = "'#{att[1]'"
>>>> You're missing a '}' here ----------^
>>>> 
>>>> does that help?
>>>> 
>>> 
>>> Nope. I am providing the surrounding function here. (It is defined inside 
>>> a class.)
>>>
>>>    def load_from_file(filename)
>>>      require 'yaml'
>>>      yaml_dict = YAML::load(File.open(filename))
>>>      object_list = []        #The list that should be returned
>>>      yaml_dict[yaml_dict.keys[0]].each do |yaml_obj|
>>>        new_obj = self.class.new
>>>        yaml_obj.each do |obj|
>>>          obj_as_list = obj.to_a
>>>          obj_as_list.each do |att|
>>>            if att[1].is_a?(String)
>>>              att[1] = "'#{att[1]}'"
>>>            end
>>>            str = "new_obj.#{att[0]} = #{att[1]}"
>>>            eval(str)
>>>          end
>>>        end
>>>        object_list << new_obj
>>>      end
>>>      object_list
>>>    end
>>> 
>>> And the error:
>>>
>>>     NameError: undefined local variable or method `att' for main:Object
>> 
>> If att[1] is, say, :att, then "#{att[1]}" is "att" and you've got a
>> dangling att. The whole eval thing seems extremely fragile (which eval
>> things usually are). I imagine there's a more robust and probably
>> shorter way to do this, but I'm not sure what the data coming in and
>> out are supposed to be like.
>> 
>> 
>> David
>> 
>
> I am almost positive that there is, given that I'm pretty much a noob at 
> ruby. The whole thing is a class_eval too. The idea is to add this function 
> to a class that has just been created based on a textfile. The function will 
> receive a file that includes a yaml description of instances of the class, 
> and the function then makes these instances and sends them back as a list. I 
> think some fragility is okay, though I'd be keen on learning better ways to 
> do this. Around the entire function is
>
> the_class.class_eval %{
> 	the function...
> }
>
> I am confused about why it doesn't work though.

Can you give some sample YAML input? I'm still not quite picturing it.


David

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