From: Robert Klemme <shortcutter@...>
Date: 2009-12-08T23:31:08+09:00
Subject: Re: convert string into a variable object

2009/12/8 David A. Black <dblack@rubypal.com>:
> HI --
>
> On Tue, 8 Dec 2009, Steve Wilhelm wrote:
>
>> Toon Willems wrote:
>>>
>>> On 07 Dec 2009, at 21:35, Ad Ad wrote:
>>>
>>>>> to do.
>>>>
>>>> doesnt require the  creation of any sort of a container variable.
>>>> --
>>>> Posted via http://www.ruby-forum.com/.
>>>>
>>>
>>> A much better way to do this would be to store the city names in a hash.
>>> your code would then be:
>>>
>>> File.open(@file). each do |x|
>>>  @hash[x] = true
>>> end
>>
>> Would it not be better to convert to symbols? That is:
>>
>> File.open(@file). each do |x|
>>  @hash[x.strip.to_sym] = true
>> end
>>
>> if @hash[:toronto]
>> or
>> if @hash[:"palo alto"]
>>
>> or
>>
>> if @hash[city.to_sym]
>
> In addition to the garbage collection issue that David M. pointed out,
> symbols seem an odd choice to me for city names. I always think of
> symbols as appropriate for label-like functionality and values taken
> from a limited set. Strings are a better choice for general
> representation of text.

I would certainly use String for city names.  Hard encoding city names
in classes which would be regenerated over and over again is not a
good solution.  Basically, you want to stick all city names as keys in
a Hash and work from there.  The mere fact that Ruby is able to
generate local, instance or global variables at runtime does not mean
it is a proper means in all cases.  The use case at hand does not call
for meta programming - it just needs a data structure which can work
with appropriate key values.  A Hash seems like a good fit here.

My 0.02EUR.

Kind regards

robert

-- 
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