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javarubycollectionsunmodifiable

Ruby equivalent of Java's Collections.unmodifiableList and Collections.unmodifiableMap

Is there a equivalent in the Ruby standard API for Java's Collections.unmodifiableList and Collections.unmodifiableMap?

Solution

  • Use freeze API:

    Prevents further modifications to obj. A RuntimeError will be raised if modification is attempted. There is no way to unfreeze a frozen object. See also Object#frozen?.

    This method returns self.

    a = [ "a", "b", "c" ]
a.freeze
a << "z"

    produces:

    prog.rb:3:in `<<': can't modify frozen array (RuntimeError)
 from prog.rb:3

    You can also use the hamster gem for other immutable data structures.