Feature #16818
Updated by sawa (Tsuyoshi Sawada) over 4 years ago
`Range#%` was introduced as an alias of `Range#step` by 14697, but it is counter-intuitive and confusing.
Iteration in the following:
```ruby
((5..14) % 3).each{|i| p i}
#>> 5
#>> 8
#>> 11
#>> 14
```
is not based on `x % y` in any sense. In fact, actually applying `% 3` to the selected elements returns a unique value `2`, and it is not obvious how this is related to the iteration.
```ruby
[5, 8, 11, 14].map{|i| i % 3}
# => [2, 2, 2, 2]
```
Rather, the concept seems to be based on `/`. Applying `/ 3` to the relevant elements returns a sequence `1, 2, 3, 4`.
```ruby
[5, 8, 11, 14].map{|i| i / 3}
# => [1, 2, 3, 4]
```
Hence, `(5..14).step(3)` can be interpreted like this: Iterate over the [equivalence class](https://en.wikipedia.org/wiki/Equivalence_class) (quotient set) of range `5..14` yielded by `/ 3`.
Notice that the number of elements in `[5, 8, 11, 14]` is 4, which is `(14 - 5 + 1) / 3.0).ceil`, but is not related to `%`.
So I propose that the alias of `Range#step` should be `Range#/`, and `Range#%` should be deprecated as soon as possible before its use accumulates:
```ruby
((5..14) / 3).each{|i| p i}
#>> 5
#>> 8
#>> 11
#>> 14
```
---
P.S.
And if `Range#%` were to be introduced at all, I would rather expect it to behave like the following:
```ruby
((5..14) % 3).each{|i| p i}
#>> 5
#>> 6
#>> 7
```
which is why I claimed above that the current `Range#%` is confusing.