From: Logan Capaldo <logancapaldo@...>
Date: 2006-03-02T04:12:17+09:00
Subject: Re: Create named objects

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On Mar 1, 2006, at 11:33 AM, kgoblin@gmail.com wrote:

>
> Roland Schmitt wrote:
>> Hello,
>>
>> want to do the following:
>>
>> name = "input"
>> clazz = "String"
>> value = "test"
>>
>> <<<some magic here>>>
>>
>> puts(input) -> "test"
>> input.class() -> String
>>
>>
>> Thanks in advance,
>>
>> Roland
>
> a pretty straight forward way is to just use the eval function on a
> string
>
> # in your insert magic here:
> evs = "#{name} = #{clazz}.new( #{value} )"
> eval( evs )

alternatively:

name =  "input"
clazz = "String"
value = "test"

(class << self; self; end).class_eval { define_method(name)  
{ const_get(clazz).new(value) } }

puts(input)
puts input.class


There are several disadvantages to this approach.
1) input is a method not  really a variable and therefore its scope  
is gonna be all sorts of wrong
2) Since it is a method, assigning to it is not necessarily going to  
work the way you want

Advantages ares that yo don't have to worry about the having seen an  
assignment to it business and you don't have to invoke the parser

Yet another method would be
instance_variable_set("@#{name}", Object.const_get(clazz).new(value))

Unfortunately now you have to refer to it  as @input. It also has  
some scoping issues.
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