Editing Immutable object (section)

=== Interning ===
The practice of always using references in place of copies of equal objects is known as ''[[intern (computer science)|interning]]''. If interning is used, two objects are considered equal if and only if their references, typically represented as pointers or integers, are equal. Some languages do this automatically: for example, [[Python (programming language)|Python]] automatically [[String intern pool|interns short strings]]. If the algorithm that implements interning is guaranteed to do so in every case that it is possible, then comparing objects for equality is reduced to comparing their pointers – a substantial gain in speed in most applications. (Even if the algorithm is not guaranteed to be comprehensive, there still exists the possibility of a [[fast path]] case improvement when the objects are equal and use the same reference.) Interning is generally only useful for immutable objects.