diff options
Diffstat (limited to 'hash.c')
| -rw-r--r-- | hash.c | 23 |
1 files changed, 18 insertions, 5 deletions
@@ -1879,11 +1879,11 @@ rb_hash_update_block_i(VALUE key, VALUE value, VALUE hash) * hsh.merge!(other_hash){|key, oldval, newval| block} -> hsh * hsh.update(other_hash){|key, oldval, newval| block} -> hsh * - * Adds the contents of <i>other_hash</i> to <i>hsh</i>. If no - * block is specified, entries with duplicate keys are overwritten - * with the values from <i>other_hash</i>, otherwise the value - * of each duplicate key is determined by calling the block with - * the key, its value in <i>hsh</i> and its value in <i>other_hash</i>. + * Adds the contents of _other_hash_ to _hsh_. If no block is specified, + * entries with duplicate keys are overwritten with the values from + * _other_hash_, otherwise the value of 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 } @@ -1893,6 +1893,19 @@ rb_hash_update_block_i(VALUE key, VALUE value, VALUE hash) * h2 = { "b" => 254, "c" => 300 } * h1.merge!(h2) { |key, v1, v2| v1 } * #=> {"a"=>100, "b"=>200, "c"=>300} + * + * Note that this method creates a shallow copy of the value in _other_hash_. + * This means that when for example Array#select! is used on one of the values + * in _other_hash_ both the original object as well as the copy will be + * modified. This is illustrated in the following example: + * + * original = { "numbers" => [10, 20, 30] } + * copy = {}.merge(original) + * + * copy["numbers"].select! { |number| number <= 20 } + * + * puts copy # => { "numbers" => [10, 20] } + * puts original # => { "numbers" => [10, 20] } */ static VALUE |