Feature #16274
Updated by sawa (Tsuyoshi Sawada) about 5 years ago
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"}
```