1. To create local variables in ruby dynamically.
Use eval method in ruby
ree-1.8.7-2010.01 > eval("local=4")
=> 4
ree-1.8.7-2010.01 > p local
4
ree-1.8.7-2010.01 > eval("local_#{1}=4")
=> 4
ree-1.8.7-2010.01 > puts local_1
4
2. To create & get instance variables dynamically in ruby.
instance_varaiable_set & instance_varaiable_get methods are provided and no need to do it using eval.
ree-1.8.7-2010.01 > (0..3).each do |i|
ree-1.8.7-2010.01 > instance_variable_set("@instance_#{i}", i*i+1)
ree-1.8.7-2010.01 ?> end
=> 0..3
ree-1.8.7-2010.01 > @instance_0
=> 1
ree-1.8.7-2010.01 > @instance_2
=> 5
3. Dynamic constant variable creation in ruby
ree-1.8.7-2010.01 > class Example
ree-1.8.7-2010.01 ?> end
=> nil
ree-1.8.7-2010.01 > Example.const_set('A',200)
=> 200
ree-1.8.7-2010.01 > Example::A
=> 200
