Hash#merge!

hash.merge! → self

hash.merge!(*other_hashes) → self

hash.merge!(*other_hashes) { |key, old_value, new_value| ... } → self

static VALUE
rb_hash_update(int argc, VALUE *argv, VALUE self)
{
    int i;
    bool block_given = rb_block_given_p();

    rb_hash_modify(self);
    for (i = 0; i < argc; i++){
        VALUE hash = to_hash(argv[i]);
        if (block_given) {
            rb_hash_foreach(hash, rb_hash_update_block_i, self);
        }
        else {
            rb_hash_foreach(hash, rb_hash_update_i, self);
        }
    }
    return self;
}

Alias of #update

Merges each of other_hashes into self; returns self.

Each argument in other_hashes must be a Hash.

With arguments and no block:

Returns self, after the given hashes are merged into it.
The given hashes are merged left to right.
Each new entry is added at the end.
Each duplicate-key entry’s value overwrites the previous value.

Example:

Example

h = {foo: 0, bar: 1, baz: 2}
h1 = {bat: 3, bar: 4}
h2 = {bam: 5, bat:6}
h.merge!(h1, h2) # => {:foo=>0, :bar=>4, :baz=>2, :bat=>6, :bam=>5}

With arguments and a block:

Returns self, after the given hashes are merged.
The given hashes are merged left to right.
Each new-key entry is added at the end.
For each duplicate key:
- Calls the block with the key and the old and new values.
- The block’s return value becomes the new value for the entry.

Example:

Example

h = {foo: 0, bar: 1, baz: 2}
h1 = {bat: 3, bar: 4}
h2 = {bam: 5, bat:6}
h3 = h.merge!(h1, h2) { |key, old_value, new_value| old_value + new_value }
h3 # => {:foo=>0, :bar=>5, :baz=>2, :bat=>9, :bam=>5}

With no arguments:

Returns self, unmodified.
The block, if given, is ignored.

Example:

Example

h = {foo: 0, bar: 1, baz: 2}
h.merge # => {:foo=>0, :bar=>1, :baz=>2}
h1 = h.merge! { |key, old_value, new_value| raise 'Cannot happen' }
h1 # => {:foo=>0, :bar=>1, :baz=>2}

See also #update #merge #rassoc #member? also in 4.1 · 4.0 · 3.4 · 3.2 · 3.1 · 3.0

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