diff --git a/hash.c b/hash.c index 169abbd52a..f9f8077765 100644 --- a/hash.c +++ b/hash.c @@ -1828,12 +1828,16 @@ rb_hash_update(hash1, hash2) * hsh.merge(other_hash){|key, oldval, newval| block} -> a_hash * * Returns a new hash containing the contents of other_hash and - * the contents of hsh, overwriting entries in hsh with - * duplicate keys with those from other_hash. + * the contents of hsh. If no block is specified, the value for + * entries with duplicate keys will be that of other_hash. Otherwise + * the value for each duplicate key is determined by calling the block + * with the key, its value in hsh and its value in other_hash. * * h1 = { "a" => 100, "b" => 200 } * h2 = { "b" => 254, "c" => 300 } * h1.merge(h2) #=> {"a"=>100, "b"=>254, "c"=>300} + * h1.merge(h2){|key, oldval, newval| newval - oldval} + * #=> {"a"=>100, "b"=>54, "c"=>300} * h1 #=> {"a"=>100, "b"=>200} * */