Maintenance Ruby 3.3 gets fixes, but no new features. Switch to Ruby 4.0 →
instance method
Data#hash
hash → integer
struct.c
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#define rb_data_hash rb_struct_hash
Redefines Object#hash (used to distinguish objects as Hash keys) so that data objects of the same class with same content would have the same hash value, and represented the same Hash key.
Example
Measure = Data.define(:amount, :unit) Measure[1, 'km'].hash == Measure[1, 'km'].hash #=> true Measure[1, 'km'].hash == Measure[10, 'km'].hash #=> false Measure[1, 'km'].hash == Measure[1, 'm'].hash #=> false Measure[1, 'km'].hash == Measure[1.0, 'km'].hash #=> false # Structurally similar data class, but shouldn't be considered # the same hash key Measurement = Data.define(:amount, :unit) Measure[1, 'km'].hash == Measurement[1, 'km'].hash #=> false