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I discovered this after playing around with object ids.
ObjectSpace._id2ref(2648)
=> :**
ObjectSpace._id2ref(6688)
=> :**
ObjectSpace._id2ref(2648) == ObjectSpace._id2ref(6688)
=> false
The first one is the symbol for the exponentiation operator;
2.send(ObjectSpace._id2ref(2648), 3)
=> 8
2.send(ObjectSpace._id2ref(6688), 3)
NoMethodError: undefined method `**' for 2:Fixnum
But the second one somehow isn't? I assume they just look the same after being passed to #print. But what is the difference? Is one of them somehow a unicode symbol?
UPDATE: The second one is probably the new double splat for keyword arguments, but I can't seem to verify this.
643
Ruby symbols are defined as “scalar value objects used as identifiers, mapping immutable strings to fixed internal values.” Essentially what this means is that symbols are immutable strings. In programming, an immutable object is something that cannot be changed.
What is the difference between a symbol and a string? A string, in Ruby, is a mutable series of characters or bytes. Symbols, on the other hand, are immutable values. Just like the integer 2 is a value.
While symbols and strings give you the same results when used as keys in hashes, they are not the same thing. A symbol is immutable while a string is mutable. You can't change a symbol once it's created. :locked on different lines in your code is the same object.
In Ruby, the at-sign ( @ ) before a variable name (e.g. @variable_name ) is used to create a class instance variable.
These commands may be illuminating:
ObjectSpace._id2ref(2648).class.ancestors
ObjectSpace._id2ref(6688).class.ancestors
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