Mutable and Immutable Objects: Ruby Study Notes - Best Ruby Guide, Ruby Tutorial

Mutable and Immutable Objects: Ruby Study Notes - Best Ruby Guide, Ruby Tutorial:

Let us understand what we are doing here - a and b are two variables both of which are pointing to a string object - Original String . We then freeze the object Original String . Hence both a and b are now pointing to the frozen object Original String . This is verified by the statements puts a.frozen? and puts b.frozen?. Next, we create a new string object New String and make variable a point to this new object New String . Variable b is still pointing to the frozen object while a is not. This verified by the last 2 statements of the program. Usage : Ruby sometimes copies objects and freezes the copies. When you use a string as a hash key, Ruby actually copies the string, freezes the copy, and uses the copy as the hash key: that way, if the original string changes later on, the hash key isn't affected. Ruby's internal file operations work from a frozen copy of a filename ...

Full article: http://rubylearning.com/satishtalim/mutable_and_immutable...