From: eregontp@... Date: 2016-05-03T09:27:26+00:00 Subject: [ruby-core:75322] [Ruby trunk Bug#12337] inconsistency between Fixnum#coerce and Bignum#coerce Issue #12337 has been updated by Benoit Daloze. I had a question about Bignum#coerce in http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/75176. I think it has limited value to have Bignum.coerce(Fixnum) or Fixnum.coerce(Bignum) return [Bignum, Bignum] instead of just the operands, as it creates a Bignum in the Fixnum range, which is inconsistent with all other methods and might cause performance problems. With #12005 this would be naturally the result with additionally no class distinction. But indeed, Fixnum.coerce(Bignum) => [Float, Float] as currently is even worse probably (and shows how rarely {Bignum,Fixnum}#coerce are used in practice). ---------------------------------------- Bug #12337: inconsistency between Fixnum#coerce and Bignum#coerce https://bugs.ruby-lang.org/issues/12337#change-58452 * Author: Akira Tanaka * Status: Open * Priority: Normal * Assignee: * ruby -v: ruby 2.4.0dev (2016-05-01 trunk 54866) [x86_64-linux] * Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN ---------------------------------------- I found 1.coerce(2.0) is [2.0, 1.0] but (2**100).coerce(2.0) raises TypeError ``` % ./ruby -ve 'p 1.coerce(2.0)' ruby 2.4.0dev (2016-05-01 trunk 54866) [x86_64-linux] [2.0, 1.0] % ./ruby -ve 'p (2**100).coerce(2.0)' ruby 2.4.0dev (2016-05-01 trunk 54866) [x86_64-linux] -e:1:in `coerce': can't coerce Float to Bignum (TypeError) from -e:1:in `
' ``` This is a documented behavior. ``` % ri Bignum.coerce|cat = Bignum.coerce (from ruby core) ------------------------------------------------------------------------------ big.coerce(numeric) -> array ------------------------------------------------------------------------------ Returns an array with both a numeric and a big represented as Bignum objects. This is achieved by converting numeric to a Bignum. A TypeError is raised if the numeric is not a Fixnum or Bignum type. (0x3FFFFFFFFFFFFFFF+1).coerce(42) #=> [42, 4611686018427387904] ``` But I think this is bad bahavior. Fixnum and Bignum should work seamlessly. For example, this exposes the platform is 32-bit or 64-bit. 2**40 is Fixnum on 32-bit environment and Bignum on 64-bit environment. So, (2**40).coerce(2.0) behaves differently: returns an array on 64-bit and raises TypeError on 32-bit platform. ``` 32bit-platform% ./ruby -ve 'p (2**40).coerce(2.0)' ruby 2.4.0dev (2016-05-01 trunk 54866) [x86_64-linux] [2.0, 1099511627776.0] 64bit-platform% ./ruby -ve 'p (2**40).coerce(2.0)' ruby 2.4.0dev (2016-05-01 trunk 54864) [i686-linux] -e:1:in `coerce': can't coerce Float to Bignum (TypeError) from -e:1:in `
' ``` I think the behavior of Bignum#coerce should be changed to match Fixnum#coerce (actually defined at Numeric). ---Files-------------------------------- int-coerce.patch (2.37 KB) -- https://bugs.ruby-lang.org/ Unsubscribe: