From: sawadatsuyoshi@gmail.com
To: ruby-core@ruby-lang.org
Subject: [ruby-core:95498] [Ruby master Feature#16274] Transform hash keys by a hash
Date: Wed, 23 Oct 2019 09:20:21 +0000 (UTC) [thread overview]
Message-ID: <redmine.journal-82273.20191023092021.7cda33fa7b93d613@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-16274.20191023090915@ruby-lang.org
Issue #16274 has been updated by sawa (Tsuyoshi Sawada).
shyouhei (Shyouhei Urabe) wrote:
> Understand the motivation (maybe that of #slice can be separated into another request).
>
> One quick question: what should happen if _both_ a block and an argument are passed at once?
Actually, I just came up with an additional idea regarding that exact point. Updated the issue.
----------------------------------------
Feature #16274: Transform hash keys by a hash
https://bugs.ruby-lang.org/issues/16274#change-82273
* Author: sawa (Tsuyoshi Sawada)
* Status: Open
* Priority: Normal
* Assignee:
* Target version:
----------------------------------------
We have `Hash#transform_keys` and its bang version to change the keys of a hash, but that requires passing a block, which assumes that the mapping from old keys to new keys follow some rule. But in reality, we frequently want to change the keys where it is difficult to provide a rule. For example, suppose we have:
```
hash = {created: 2019-10-23 17:54:46 +0900, updated: 2019-10-23 17:59:18 +0900, author: "foo"}
```
and want to achieve:
```
{created_at: 2019-10-23 17:54:46 +0900, update_time: 2019-10-23 17:59:18 +0900, author: "foo"}
```
I request an option to change the keys of a hash not by giving a block, but by passing a hash. I came up with two options.
### 1. Argument for `Hash#transform_keys` and its bang version
Allow `Hash#transform_keys` to optionally take a hash argument instead of a block.
```
hash.transform_keys({created: :created_at, updated: :update_time})
# => {created_at: 2019-10-23 17:54:46 +0900, update_time: 2019-10-23 17:59:18 +0900, author: "foo"}
```
### 2. Argument for `Hash#slice` and the counterparts in other classes
Since `Hash#slice` is often the first step of modifying a hash into some other hash form, it makes sense to let it take an optional hash argument.
```
hash.slice(:created, :author, transform_keys: {created: :created_at})
# => {created_at: 2019-10-23 17:54:46 +0900, author: "foo"}
```
With option 1, it could make sense to even allow a hash argument and a block simultaneously:
```
hash.transform_keys({created: :created_at, updated: :update_time}, &:to_s)
# => {"created_at" => 2019-10-23 17:54:46 +0900, "update_time" => 2019-10-23 17:59:18 +0900, "author" => "foo"}
```
--
https://bugs.ruby-lang.org/
next prev parent reply other threads:[~2019-10-23 9:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <redmine.issue-16274.20191023090915@ruby-lang.org>
2019-10-23 9:09 ` [ruby-core:95496] [Ruby master Feature#16274] Transform hash keys by a hash sawadatsuyoshi
2019-10-23 9:16 ` [ruby-core:95497] " shyouhei
2019-10-23 9:20 ` sawadatsuyoshi [this message]
2019-10-23 9:37 ` [ruby-core:95499] " duerst
2019-10-23 19:46 ` [ruby-core:95513] " shevegen
2019-12-20 7:28 ` [ruby-core:96369] " knu
2019-12-20 7:31 ` [ruby-core:96370] " matz
2019-12-23 4:53 ` [ruby-core:96416] " duerst
2019-12-23 8:54 ` [ruby-core:96420] " sawadatsuyoshi
2019-12-23 8:57 ` [ruby-core:96421] " sawadatsuyoshi
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