[#58149] [ruby-trunk - Feature #9076][Open] New one-argument block syntax: &. — "asterite (Ary Borenszweig)" <ary@...>
23 messages
2013/11/04
[#58259] [ruby-trunk - Feature #9099][Open] Train emoji lambda operator — "charliesome (Charlie Somerville)" <charliesome@...>
9 messages
2013/11/10
[#58312] [ruby-trunk - Feature #9107][Open] Introduce YES and NO as aliases of true and false — "gsamokovarov (Genadi Samokovarov)" <gsamokovarov@...>
5 messages
2013/11/13
[#58350] [ruby-trunk - Feature #9113][Open] Ship Ruby for Linux with jemalloc out-of-the-box — "sam.saffron (Sam Saffron)" <sam.saffron@...>
59 messages
2013/11/15
[#60851] Re: [ruby-trunk - Feature #9113][Open] Ship Ruby for Linux with jemalloc out-of-the-box
— Eric Wong <normalperson@...>
2014/02/19
Btw, I also hope to experiment with a slab allocator since many internal
[#62721] [ruby-trunk - Feature #9113] Ship Ruby for Linux with jemalloc out-of-the-box
— nobu@...
2014/05/24
Issue #9113 has been updated by Nobuyoshi Nakada.
[#62735] [ruby-trunk - Feature #9113] Ship Ruby for Linux with jemalloc out-of-the-box
— normalperson@...
2014/05/25
Issue #9113 has been updated by Eric Wong.
[#58391] [ruby-trunk - Bug #9119][Assigned] TestTime#test_marshal_broken_offset broken under MinGW — "luislavena (Luis Lavena)" <luislavena@...>
10 messages
2013/11/17
[#58396] [ruby-trunk - Bug #9121][Open] [PATCH] Remove rbtree implementation of SortedSet due to performance regression — "xshay (Xavier Shay)" <contact@...>
15 messages
2013/11/18
[#58404] [ruby-trunk - Feature #9123][Open] Make Numeric#nonzero? behavior consistent with Numeric#zero? — "sferik (Erik Michaels-Ober)" <sferik@...>
40 messages
2013/11/18
[#58411] [ruby-trunk - Bug #9124][Open] TestSocket errors in test-all on Arch 64-bit — "jonforums (Jon Forums)" <redmine@...>
14 messages
2013/11/18
[#58515] [ruby-trunk - Bug #9124] TestSocket errors in test-all on Arch 64-bit
— "jonforums (Jon Forums)" <redmine@...>
2013/11/23
[#58841] [ruby-trunk - Bug #9124] TestSocket errors in test-all on Arch 64-bit
— "jonforums (Jon Forums)" <redmine@...>
2013/12/04
[#58842] Re: [ruby-trunk - Bug #9124] TestSocket errors in test-all on Arch 64-bit
— Eric Wong <normalperson@...>
2013/12/04
"jonforums (Jon Forums)" <[email protected]> wrote:
[#58452] [ruby-trunk - Bug #9133][Open] logger rotates log files more than expected — "no6v (Nobuhiro IMAI)" <nov@...>
8 messages
2013/11/21
[#58473] Object identity for string hash keys — Andrew Vit <andrew@...>
I'm not sure if this is a bug. I'm creating a hash like this:
5 messages
2013/11/21
[#58490] Re: [ruby-cvs:50910] drbrain:r43767 (trunk): * lib/rubygems: Update to RubyGems master 50a8210. Important changes — Tanaka Akira <akr@...>
2013/11/22 <[email protected]>:
4 messages
2013/11/22
[#58492] Re: [ruby-cvs:50910] drbrain:r43767 (trunk): * lib/rubygems: Update to RubyGems master 50a8210. Important changes
— Eric Wong <normalperson@...>
2013/11/22
Tanaka Akira <[email protected]> wrote:
[#58496] [ruby-trunk - Feature #9140][Open] Allow each_with_index to get start index — "rosenfeld (Rodrigo Rosenfeld Rosas)" <rr.rosas@...>
8 messages
2013/11/22
[#58545] [ruby-trunk - Feature #9145][Open] Queue#pop(true) return nil if empty instead of raising ThreadError — "jsc (Justin Collins)" <redmine@...>
9 messages
2013/11/24
[#58599] [ruby-trunk - Bug #9159][Open] [patch] use rb_fstring for internal strings — "tmm1 (Aman Gupta)" <[email protected]>
5 messages
2013/11/26
[#58653] [ruby-trunk - Bug #9170][Open] Math.sqrt returns different types when mathn is included; breaks various gems - this bug can be reproduced in Ruby 1.8 as well — "kranzky (Jason Hutchens)" <JasonHutchens@...>
7 messages
2013/11/28
[#58719] [ruby-trunk - Feature #5446] at_fork callback API — "tmm1 (Aman Gupta)" <[email protected]>
6 messages
2013/11/30
[ruby-core:58356] [ruby-trunk - Feature #9108] Hash sub-selections
From:
"wardrop (Tom Wardrop)" <tom@...>
Date:
2013-11-15 05:48:05 UTC
List:
ruby-core #58356
Issue #9108 has been updated by wardrop (Tom Wardrop).
Enumerator includes Enumerable, as does Hash. Enumerator introduces a few new methods that revolve around the concept of a cursor, but otherwise everything else comes from Enumerable.
My whole point is that for anyone using #reject or #select to retrieve an Enumerator from a Hash (which really no one should be doing), there's a good chance their code will still work, as long as they're not using the extra cursor functionality exclusive to Enumerators.
Hash#select(*keys) is such an appropriate interface for obtaining a subset of a hash, as that's exactly what the #select and #reject methods are intended for. It would be silly in my opinion to introduce a new method.
The question is, should Hash#select without arguments return a copy of the original hash, or an empty hash? Thinking about it, I'd say Hash#select should return an empty hash if no arguments are given, though this completely breaks compatibility for anyone using Hash#select (without arguments) as a means of obtaining an enumerator. Hash#reject without an argument should definitely return a full copy of the original hash.
----------------------------------------
Feature #9108: Hash sub-selections
https://bugs.ruby-lang.org/issues/9108#change-42953
Author: wardrop (Tom Wardrop)
Status: Open
Priority: Normal
Assignee:
Category:
Target version:
=begin
Hi,
I seem to regularly have the requirement to work on a sub-set of key/value pairs within a hash. Ruby doesn't seem to provide a concise means of selecting a sub-set of keys from a hash. To give an example of what I mean, including how I currently achieve this:
sounds = {dog: 'woof', cat: 'meow', mouse: 'squeak', horse: 'nay', cow: 'moo'}
domestic_sounds = sounds.select { |k,v| [:dog, :cat].include? k } #=> {dog: 'woof', cat: 'meow'}
I think a more concise and graceful solution to this would be to allow the Hash#[] method to take multiple arguments, returning a sub-hash, e.g.
domestic_sounds = sounds[:dog, :cat] #=> {dog: 'woof', cat: 'meow'}
I had a requirement in the current project I'm working on to concatenate two values in a hash. If this proposed feature existed, I could of just done this...
sounds[:dog, :cat].values.join #=> 'woofmeow'
You could do something similar for the setter also...
sounds[:monkey, :bat] = 'screech'
sounds #=> {dog: 'woof', cat: 'meow', mouse: 'squeak', horse: 'nay', cow: 'moo', monkey: 'screech', bat: 'screech'}
Concise, convenient and readable. Thoughts?
=end
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