From: "nobu (Nobuyoshi Nakada)" <nobu@...>
Date: 2013-06-25T11:01:09+09:00
Subject: [ruby-core:55641] [CommonRuby - Feature #8568] Introduce RbConfig value for native word size, to avoid Fixnum#size use


Issue #8568 has been updated by nobu (Nobuyoshi Nakada).


In current CRuby, Fixnum is always limited as long, so Fixnum#size represents sizeof(long), not word size.
But it depends on what you define "word" as, of course.
If you mean SIZEOF_VALUE by "word size", it's simply a bug to use Fixnum#size for that purpose.

A way to achieve size of a pointer is `[""].pack("p").size` currently.
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Feature #8568: Introduce RbConfig value for native word size, to avoid Fixnum#size use
https://bugs.ruby-lang.org/issues/8568#change-40125

Author: headius (Charles Nutter)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 


Fixnum#size is not really useful to represent native word size across all platforms and implementations. On JRuby, for example, our Fixnum is always represented as a 64-bit Java "long" value, regardless of the underlying native platform. There may be other implementations that fix Fixnum's size to a specific bit width as well. Therefore, using Fixnum#size to determine the size of a word on the underlying native platform is not reliable.

I propose two additions to Ruby:

1. RbConfig value "word_size" for native word size. This could reflect bit size (32, 64) or byte size (4, 8).

2. A constant, somewhere in Ruby, to provide access to this value more directly. I'm not sure where this should go. ObjectSpace::WORD_SIZE?


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