Issue #18984 has been updated by mame (Yusuke Endoh). Discussed at the dev meeting. @matz said that he wanted to try to fix the behavior of Range#size instead of changing the document. If the incompatibilty is found significant, it will be reconsidered. ```ruby (0.51..5.quo(2)).size #=> TypeError (..0).size #=> TypeError ``` ---------------------------------------- Misc #18984: Doc for Range#size for Float/Rational does not make sense https://bugs.ruby-lang.org/issues/18984#change-104902 * Author: masasakano (Masa Sakano) * Status: Open * Priority: Normal ---------------------------------------- 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. -- https://bugs.ruby-lang.org/