From: Brian Candler <b.candler@...>
Date: 2008-09-29T17:23:31+09:00
Subject: Re: Variable name to string

reuben doetsch wrote:
> I would like to get the name of the variable in string form, any way 
> this is
> possible?
> 
> var = 5
> puts var.foo  #Want this ti put var

Well, you can do this the other way round:

  varname = "foo"
  eval("#{varname} = 5")
  puts varname

But you almost certainly *don't* want to do this. This is abuse of both 
local variables and eval, and it means you're solving the wrong problem, 
or solving the problem in the wrong way.

Things you might reasonably do dynamically are:

* invoke methods on an object

obj = "hello"
meth = "upcase"
p obj.send(meth)    # "HELLO"

* set and read instance variables of an object

obj = Object.new
ivar = "@foo"
obj.instance_variable_set(ivar, 5)
p obj.instance_variable_get(ivar)    # 5

* locate a constant or class by name

klassname = "String"
klass = Object.const_get(klassname)
obj = klass.new
p obj               # ""

* add methods in a module to an object

module Foo
  def double
    self * 2
  end
end
obj = "hello"
obj.extend Foo
p obj.double        # "hellohello"

* define new methods in a class or an object

Leave this one until you know the language more deeply :-)
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