Use a string to access a local variable by name

Question

I'm new to this but I have the following code:

when /^read (.+)$/
   puts "Reading #{$1}:"
   puts $1.description.downcase

I would like to use $1 as a variable that I can call methods on, currently the interpreter returns a "NoMethodError: undefined method 'description' for "Door":String".

Edit:

For example:

door = Item.new( :name => "Door", :description => "a locked door" )
key  = Item.new( :name => "Key",  :description => "a key"         )

Answer 1

You need to provide more details of your code setup to get a good answer (or for me to figure out which question this is a duplicate of :). What kind of variables are referenced by $1? Here are some guesses:

1. If this is actually a method on the same instance, you can invoke this method by:

   # Same as "self.foo" if $1 is "foo"
   self.send($1).description.downcase 
   

2. If these are instance variables, then:

   # Same as "@foo.description.downcase"
   instance_variable_get(:"@#{$1}").description.downcase
   

3. If these are local variables, you can't do it directly, and you should change your code to use a Hash:

   objs = {
     'foo' => ...,
     'key' => Item.new( :name => "Key", :description => "a key" )
   }
   objs['jim'] = ...
   case some_str
     when /^read (.+)$/
       puts "Reading #{$1}:"
       puts objs[$1].description.downcase
   end