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[DOC] Tweaks for Hash#update

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Burdette Lamar 2025-03-31 13:47:20 -05:00 • committed by GitHub
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Notes: git 2025-03-31 18:47:37 +00:00 
Merged: https://github.com/ruby/ruby/pull/12985

Merged-By: peterzhu2118 <peter@peterzhu.ca>
1 changed files with 33 additions and 6 deletions
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hash.c
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@ -4168,13 +4168,40 @@ rb_hash_update_block_i(VALUE key, VALUE value, VALUE hash)
* update(*other_hashes) -> self * update(*other_hashes) -> self
* update(*other_hashes) { |key, old_value, new_value| ... } -> self * update(*other_hashes) { |key, old_value, new_value| ... } -> self
* *
* Like Hash#merge, but modifies and returns +self+ instead of a new hash: * Updates values and/or adds entries to +self+; returns +self+.
* *
* season = {AB: 75, H: 20, HR: 3, SO: 17, W: 11, HBP: 3} * Each argument +other_hash+ in +other_hashes+ must be a hash.
* today = {AB: 3, H: 1, W: 1} *
* yesterday = {AB: 4, H: 2, HR: 1} * With no block given, for each successive entry +key+/+new_value+ in each successive +other_hash+:
* season.update(yesterday, today) {|key, old_value, new_value| old_value + new_value } *
* # => {AB: 82, H: 23, HR: 4, SO: 17, W: 12, HBP: 3} * - If +key+ is in +self+, sets <tt>self[key] = new_value</tt>, whose position is unchanged:
*
* h0 = {foo: 0, bar: 1, baz: 2}
* h1 = {bar: 3, foo: -1}
* h0.update(h1) # => {foo: -1, bar: 3, baz: 2}
*
* - If +key+ is not in +self+, adds the entry at the end of +self+:
*
* h = {foo: 0, bar: 1, baz: 2}
* h.update({bam: 3, bah: 4}) # => {foo: 0, bar: 1, baz: 2, bam: 3, bah: 4}
*
* With a block given, for each successive entry +key+/+new_value+ in each successive +other_hash+:
*
* - If +key+ is in +self+, fetches +old_value+ from <tt>self[key]</tt>,
* calls the block with +key+, +old_value+, and +new_value+,
* and sets <tt>self[key] = new_value</tt>, whose position is unchanged :
*
* season = {AB: 75, H: 20, HR: 3, SO: 17, W: 11, HBP: 3}
* today = {AB: 3, H: 1, W: 1}
* yesterday = {AB: 4, H: 2, HR: 1}
* season.update(yesterday, today) {|key, old_value, new_value| old_value + new_value }
* # => {AB: 82, H: 23, HR: 4, SO: 17, W: 12, HBP: 3}
*
* - If +key+ is not in +self+, adds the entry at the end of +self+:
*
* h = {foo: 0, bar: 1, baz: 2}
* h.update({bat: 3}) { fail 'Cannot happen' }
* # => {foo: 0, bar: 1, baz: 2, bat: 3}
* *
* Related: see {Methods for Assigning}[rdoc-ref:Hash@Methods+for+Assigning]. * Related: see {Methods for Assigning}[rdoc-ref:Hash@Methods+for+Assigning].
*/ */