Symbols are immuable identifiers commonly used in hashes or to refer to method names. They are constructed with the syntax :some_symbol, or with the .to_sym and .intern methods. Being immutable, once created they cannot be changed.
When used for hash keys, symbols can take on a different syntax (resembling Python dictionaries). The : is moved to the end of the key and the => is dropped, like such:
numbers = {
one: 1,
two: "two",
three: 3,
}Symbols should be used over strings wherever possible. Iterating over the above hash using string keys would take twice as long.
Strictly speaking, a symbol is an instance of the Symbol class. It cannot be publically instanted, but is implicitly done so when a new symbol is created.
- https://medium.com/rubycademy/symbol-in-ruby-daca5abd4ab2
- Codecademy Ruby track