[ruby-core:107710] [Ruby master Feature#18596] Enhance the syntax for getting values in existing arrays.

Issue #18596 has been updated by Eregon (Benoit Daloze).


sawa (Tsuyoshi Sawada) wrote in #note-2:
> This idea is a duplicate of #15950

Actually not, the suggested semantic is equivalent to `array[2..size-1]` in this issue, not `array[-2..-1]` or so.
Which makes it all the clearer a negative number there is just confusing.

Anyway, this was already rejected by matz in #15950 and it seems the OP didn't know the Range is the idiomatic and existing way for this.



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Feature #18596: Enhance the syntax for getting values in existing arrays.
https://bugs.ruby-lang.org/issues/18596#change-96631

* Author: jackmaple (maple jack)
* Status: Rejected
* Priority: Normal
----------------------------------------
Hello everyone.
Is it possible to enhance the value syntax in arrays, currently we can pass one or two parameters in the array to take values.
``` ruby
[1,2,3,4,5,6,7,8,9][2]    #result=3
[1,2,3,4,5,6,7,8,9][2,8]  #result=[3, 4, 5, 6, 7, 8, 9]
[1,2,3,4,5,6,7,8,9][-1]   #result=9
```
Although negative values are supported (from back to front), they are not supported as the second parameter.
The following example is wrong and will not get the desired result.
**Is it possible to make the second parameter also support negative values?**
``` ruby
[1,2,3,4,5,6,7,8,9][2,-1] #result=nil,the expected result is from index 2 to the end
```
Sometimes we want to get interval values with step size.
``` ruby
[1,2,3,4,5,6,7,8,9][(2..8).step(2)] #result=[3, 5, 7, 9]
```
**Is it possible to add a third parameter to the array value syntax in order to simplify the syntax?**
for example:
``` ruby
[1,2,3,4,5,6,7,8,9][2,8,2] #result=[3, 5, 7, 9]
```
thanks.




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