Issue #19931 has been updated by byroot (Jean Boussier). I may be wrong, but my understanding of it is that it's so the right hand side isn't always casted to the left-hand side type. If `to_int` was invoked when doing `Integer + something`, then `1 + 1.5` would be `1 + (1.5).to_int` and would return `2` instead of `2.5`. Hence why numerics use `coerce` instead. ---------------------------------------- Misc #19931: to_int is not for implicit conversion? https://bugs.ruby-lang.org/issues/19931#change-104946 * Author: Dan0042 (Daniel DeLorme) * Status: Open * Priority: Normal ---------------------------------------- While reviewing some implicit vs explicit conversion concepts, I discovered that arithmetic operations do not perform the implicit conversion I expected from #to_int ```ruby o = Object.new def o.to_int; 1; end 1 + o #TypeError ``` I understand there's the whole #coerce thing for numbers, but I had expected #to_int to fit neatly into this and cause the object to be implicitly coerced to Integer. So basically I thought that #to_i was for explicit conversion and #to_int for implicit conversion; is that not the case? Most of the internet seems to think that (to_int : to_i) relationship is like (to_str : to_s). But I can't seems to find authoritative documentation on the topic. -- https://bugs.ruby-lang.org/