[ruby-core:96364] [Ruby master Misc#16436] hash missing #last method, make it not so consistent (it has first)

Issue #16436 has been updated by zw963 (Wei Zheng).


zw963 (Wei Zheng) wrote:
> ``` ruby
> (pry):main(0)> h = {x:1, y:2, z:3}
> {
>     :x => 1,
>     :y => 2,
>     :z => 3
> }
> (pry):main(0)> h.first
> [
>     :x,
>     1
> ]
> (pry):main(0)> h.first.first
> :x
> (pry):main(0)> h.first.last
> 1
> ```
> 
> last method not exist.
> 
> ```ruby
> (pry):main(0)> h.last
> 
> Exception: NoMethodError: undefined method `last' for {:x=>1, :y=>2, :z=>3}:Hash
> ```
> 
> We have to use #to_a to make last working.
> 
> ```ruby
> (pry):main(0)> h.to_a.last
> [
>     :z,
>     3
> ]
> 
> (pry):main(0)> h.to_a.last.first
> :z
> (pry):main(0)> h.to_a.last.last
> 3
> ```



sawa (Tsuyoshi Sawada) wrote:
> What is this issue? Is it just a note to everyone, or are you claiming this to be a bug, or is it a feature request?

Sorry, this issue not a bug, i knew Hash#first come from Enumerable, the reason i issue it is:  i love ruby language, use it days and days, 
when encountering some inconsistencies things, i expect to give some feedback, and what i thought.

So, for this issue, the question is:

why Array include Enumerable module,  and implement Array#first Array#last method, if we should do same things for Hash?
make this language more elegant?



----------------------------------------
Misc #16436: hash missing #last method, make it not so consistent (it has first)
https://bugs.ruby-lang.org/issues/16436#change-83274

* Author: zw963 (Wei Zheng)
* Status: Open
* Priority: Normal
* Assignee: 
----------------------------------------
``` ruby
(pry):main(0)> h = {x:1, y:2, z:3}
{
    :x => 1,
    :y => 2,
    :z => 3
}
(pry):main(0)> h.first
[
    :x,
    1
]
(pry):main(0)> h.first.first
:x
(pry):main(0)> h.first.last
1
```

last method not exist.

```ruby
(pry):main(0)> h.last

Exception: NoMethodError: undefined method `last' for {:x=>1, :y=>2, :z=>3}:Hash
```

We have to use #to_a to make last working.

```ruby
(pry):main(0)> h.to_a.last
[
    :z,
    3
]

(pry):main(0)> h.to_a.last.first
:z
(pry):main(0)> h.to_a.last.last
3
```






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