From: "alexeymuranov (Alexey Muranov)" <redmine@...>
Date: 2012-10-30T07:12:47+09:00
Subject: [ruby-core:48550] [ruby-trunk - Feature #6973] Add an #integral? method to Numeric to test for whole-number values


Issue #6973 has been updated by alexeymuranov (Alexey Muranov).


>  >>   Floats are precise, just like Integers are.  *Operations* on floats are
>  >>   not accurate, and that's where the confusion comes from.  That's
>  >>   inherent to the representation and something you've got to deal with
>  >>   anyway, so I certainly don't see this test as making that problem worse.
>  >
>  > Your points is valid as long as we can distinguish a Float that includes
>  > error from a Float that includes no error, such as, just created by a
>  > Float literal, or by only accurate operations (no overflow, no indivisible
>  > division, ...).
>  > But in fact, we cannot distinguish them.  We conservatively have to think
>  > that any Float object includes an error, I think.
>  
>  So if I knowingly and correctly construct a calculation which cannot 
>  contain such an error, Ruby should tell me that it's wrong?
>  

I guess the question is: what would be a point in calling this method on a Float?  A Float value is rarely exact in the sense that it rarely coincides with the real-world value which it models.
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Feature #6973: Add an #integral? method to Numeric to test for whole-number values
https://bugs.ruby-lang.org/issues/6973#change-31933

Author: regularfry (Alex Young)
Status: Assigned
Priority: Normal
Assignee: mrkn (Kenta Murata)
Category: core
Target version: next minor


Numeric#integer? checks whether an instance is an Integer.  It is often useful to check whether the value of a non-Integer variable is actually a whole number, and the #integer? method doesn't help here.

This patch adds Numeric#integral?, which performs this check.


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