Issue #19236 has been updated by mame (Yusuke Endoh). Discussed at the dev meeting. @matz said that `Hash.create(capacity: 4096)` is acceptable (unless it conflicts with any major gems). However, several participants including @ko1 were a little cautious about introducing the new terminology "create" into Ruby core, and matz understood that. @matsuda and @mame prefer `Hash.new(capacity: 4096)`. This is a bit incompatible, but we searched gem-codesearch with the query `'\bHash\.new\(\w+: '` and found less than 20 results (manually excluding `Foo::Bar::Hash.new(...)` which is perhaps different from `::Hash`). Moreover, some of the results seemed to misunderstand `Hash.new(foo: 1)` as `{ foo: 1 }`. (The most examples are rspec; maybe because `let(:option) { { foo: 1 } }` looks bad, people inadvertently rewrote it with `let(:option) { Hash.new(foo: 1) }`.) Therefore, how about deprecating giving the keyword to `Hash.new` and then introducing `Hash.new(capacity: 4096)`? @matz said this is also acceptable if the incompatibility is not a big problem. (Off-topic: `Array.new(capacity: 4096)` is not yet available; I wonder if people want `Hash.new(capacity: 4096)` more than Array?) ---------------------------------------- Feature #19236: Allow to create hashes with a specific capacity from Ruby https://bugs.ruby-lang.org/issues/19236#change-101342 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal * Target version: 3.3 ---------------------------------------- Followup on [Feature #18683] which added a C-API for this purpose. Various protocol parsers such as Redis `RESP3` or `msgpack`, have to create hashes, and they know the size in advance. For efficiency, it would be preferable if they could directly allocate a Hash of the necessary size, so that large hashes wouldn't cause many re-alloccations and re-hash. `String` and `Array` both already offer similar APIs: ```ruby String.new(capacity: XXX) Array.new(XX) / rb_ary_new_capa(long) ``` However there's no such public API for Hashes in Ruby land. ### Proposal I think `Hash` should have a way to create a new hash with a `capacity` parameter. The logical signature of `Hash.new(capacity: 1000)` was deemed too incompatible in [Feature #18683]. @Eregon proposed to add `Hash.create(capacity: 1000)`. -- https://bugs.ruby-lang.org/

Issue #19236 has been updated by mame (Yusuke Endoh). byroot (Jean Boussier) wrote in #note-4: That would be the fastest way. Fortunately, it raises an error: `Array.new(capacity: 4096) #=> no implicit conversion of Hash into Integer (TypeError)`. So I don't see a big problem with changing this. Anyway, I think we need a separate ticket if we introduce it. ---------------------------------------- Feature #19236: Allow to create hashes with a specific capacity from Ruby https://bugs.ruby-lang.org/issues/19236#change-101421 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal * Target version: 3.3 ---------------------------------------- Followup on [Feature #18683] which added a C-API for this purpose. Various protocol parsers such as Redis `RESP3` or `msgpack`, have to create hashes, and they know the size in advance. For efficiency, it would be preferable if they could directly allocate a Hash of the necessary size, so that large hashes wouldn't cause many re-alloccations and re-hash. `String` and `Array` both already offer similar APIs: ```ruby String.new(capacity: XXX) Array.new(XX) / rb_ary_new_capa(long) ``` However there's no such public API for Hashes in Ruby land. ### Proposal I think `Hash` should have a way to create a new hash with a `capacity` parameter. The logical signature of `Hash.new(capacity: 1000)` was deemed too incompatible in [Feature #18683]. @Eregon proposed to add `Hash.create(capacity: 1000)`. -- https://bugs.ruby-lang.org/

Issue #19236 has been updated by Dan0042 (Daniel DeLorme). Previousy, a `capacity` reader/writer was suggested by @byroot in #18683#note-2 I would like to see this idea considered more seriously because 1. It doesn't need to change anything to the initialize arguments of Array/Hash/String, which are already quite complex enough 2. The same API can be used for any class; it's nicely consistent and easy to remember 3. It's more versatile, as it can be used more than once after object creation, ex: ```ruby buffer = String.new #this example is with String, but the same could apply to Hash/Array while line = gets #increase buffer capacity by chunks of 10k buffer.capacity += 10000 if buffer.capacity < buffer.bytesize + line.bytesize buffer << line end buffer.capacity = 0 #trim buffer to minimal size (aka "right-size") buffer.capacity == buffer.bytesize #=> true ``` ---------------------------------------- Feature #19236: Allow to create hashes with a specific capacity from Ruby https://bugs.ruby-lang.org/issues/19236#change-102979 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal * Target version: 3.3 ---------------------------------------- Followup on [Feature #18683] which added a C-API for this purpose. Various protocol parsers such as Redis `RESP3` or `msgpack`, have to create hashes, and they know the size in advance. For efficiency, it would be preferable if they could directly allocate a Hash of the necessary size, so that large hashes wouldn't cause many re-alloccations and re-hash. `String` and `Array` both already offer similar APIs: ```ruby String.new(capacity: XXX) Array.new(XX) / rb_ary_new_capa(long) ``` However there's no such public API for Hashes in Ruby land. ### Proposal I think `Hash` should have a way to create a new hash with a `capacity` parameter. The logical signature of `Hash.new(capacity: 1000)` was deemed too incompatible in [Feature #18683]. @Eregon proposed to add `Hash.create(capacity: 1000)`. -- https://bugs.ruby-lang.org/

Issue #19236 has been updated by byroot (Jean Boussier). That seems like a very handwavy argument to me. I really don't see how the two could possibly be confused. ---------------------------------------- Feature #19236: Allow to create hashes with a specific capacity from Ruby https://bugs.ruby-lang.org/issues/19236#change-102985 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal * Target version: 3.3 ---------------------------------------- Followup on [Feature #18683] which added a C-API for this purpose. Various protocol parsers such as Redis `RESP3` or `msgpack`, have to create hashes, and they know the size in advance. For efficiency, it would be preferable if they could directly allocate a Hash of the necessary size, so that large hashes wouldn't cause many re-alloccations and re-hash. `String` and `Array` both already offer similar APIs: ```ruby String.new(capacity: XXX) Array.new(XX) / rb_ary_new_capa(long) ``` However there's no such public API for Hashes in Ruby land. ### Proposal I think `Hash` should have a way to create a new hash with a `capacity` parameter. The logical signature of `Hash.new(capacity: 1000)` was deemed too incompatible in [Feature #18683]. @Eregon proposed to add `Hash.create(capacity: 1000)`. -- https://bugs.ruby-lang.org/

Issue #19236 has been updated by byroot (Jean Boussier). This was discussed in the last dev meeting. The conclusion was: ---------------------------------------- Feature #19236: Allow to create hashes with a specific capacity from Ruby https://bugs.ruby-lang.org/issues/19236#change-103156 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal * Target version: 3.3 ---------------------------------------- Followup on [Feature #18683] which added a C-API for this purpose. Various protocol parsers such as Redis `RESP3` or `msgpack`, have to create hashes, and they know the size in advance. For efficiency, it would be preferable if they could directly allocate a Hash of the necessary size, so that large hashes wouldn't cause many re-alloccations and re-hash. `String` and `Array` both already offer similar APIs: ```ruby String.new(capacity: XXX) Array.new(XX) / rb_ary_new_capa(long) ``` However there's no such public API for Hashes in Ruby land. ### Proposal I think `Hash` should have a way to create a new hash with a `capacity` parameter. The logical signature of `Hash.new(capacity: 1000)` was deemed too incompatible in [Feature #18683]. @Eregon proposed to add `Hash.create(capacity: 1000)`. -- https://bugs.ruby-lang.org/

Issue #19236 has been updated by byroot (Jean Boussier). Status changed from Closed to Open Target version deleted (3.3) Reopening as the merged commit is the Ruby 3.3 part. I'll implement the 3.4 next year. ---------------------------------------- Feature #19236: Allow to create hashes with a specific capacity from Ruby https://bugs.ruby-lang.org/issues/19236#change-103242 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal ---------------------------------------- Followup on [Feature #18683] which added a C-API for this purpose. Various protocol parsers such as Redis `RESP3` or `msgpack`, have to create hashes, and they know the size in advance. For efficiency, it would be preferable if they could directly allocate a Hash of the necessary size, so that large hashes wouldn't cause many re-alloccations and re-hash. `String` and `Array` both already offer similar APIs: ```ruby String.new(capacity: XXX) Array.new(XX) / rb_ary_new_capa(long) ``` However there's no such public API for Hashes in Ruby land. ### Proposal I think `Hash` should have a way to create a new hash with a `capacity` parameter. The logical signature of `Hash.new(capacity: 1000)` was deemed too incompatible in [Feature #18683]. @Eregon proposed to add `Hash.create(capacity: 1000)`. -- https://bugs.ruby-lang.org/