[ruby-core:109775] [Ruby master Misc#18984] Doc for Range#size for Float/Rational does not make sense
From:
"Eregon (Benoit Daloze)" <noreply@...>
Date:
2022-08-29 15:03:21 UTC
List:
ruby-core #109775
Issue #18984 has been updated by Eregon (Benoit Daloze).
Please do not assign ruby-core, that sends too many emails.
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Misc #18984: Doc for Range#size for Float/Rational does not make sense
https://bugs.ruby-lang.org/issues/18984#change-99011
* Author: masasakano (Masa Sakano)
* Status: Open
* Priority: Normal
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When `Range` consists of any Numeric, according to [Official docs for Ruby-3.1.2](https://ruby-doc.org/core-3.1.2/Range.html#method-i-size), `Range#size` should,
> Returns the count of elements in self if both begin and end values are numeric;
Indeed, when `Range` consists of only `Integer`, this makes sense.
However, when the begin value of `Range` is a `Float` or `Rational`, "*the count of elements*" does not make sense. Such Ranges are not iteratable, suggesting there are no such things as "elements":
```ruby
(0.51..5.quo(2)).each{} # => TypeError
```
Yet, `Range#size` of such Ranges returns an Integer
```ruby
(0.51..5.quo(2)).size # => 2
```
It seems both begin and end values of a Range are rounded (`Numeric#round`) to the nearest Integer before `Range#size` is calculated.
If this is the specification, I suggest it should be clearly stated in the [Official docs](https://ruby-doc.org/core-3.1.2/Range.html#method-i-size), avoiding the confusing expression "the count of elements", because "elements" are not unambiguously defined for Range of Float/Rational.
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