Message 59656 - Python tracker

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Author	mark.dickinson
Recipients	facundobatista, gvanrossum, jyasskin, mark.dickinson, rhettinger
Date	2008-01-10.03:51:14
SpamBayes Score	0.018579822
Marked as misclassified	No
Message-id	<[email protected]>
In-reply-to

Content
Allowing automatic coercion to and from Decimal sounds dangerous and complicated to me. Mightn't it be safer just to disallow this (at least for now)? I think something like trim() (find the closest rational approximation with denominator bounded by a given integer) would be useful to have as a Rational method, but probably only for explicit use. I'm still worried about equality tests: is it possible to give a good reason why Decimal("2.5") == Rational(5, 2) should return False, while Rational(5, 2) == 2.5 returns True. Can someone articulate some workable principle that dictates when an int/float/complex/Rational/Decimal instance compares equal to some other int/float/complex/Rational/Decimal instance of possibly different type but the same numerical value?

Allowing automatic coercion to and from Decimal sounds dangerous and 
complicated to me.  Mightn't it be safer just to disallow this (at least for 
now)?

I think something like trim()  (find the closest rational approximation with 
denominator bounded by a given integer) would be useful to have as a Rational 
method, but probably only for explicit use.

I'm still worried about equality tests:  is it possible to give a good reason 
why Decimal("2.5") == Rational(5, 2) should return False, while Rational(5, 2) 
== 2.5 returns True.  Can someone articulate some workable principle that 
dictates when an int/float/complex/Rational/Decimal instance compares equal to 
some other int/float/complex/Rational/Decimal instance of possibly different 
type but the same numerical value?

History
Date	User	Action	Args
2008-01-10 03:51:17	mark.dickinson	set	spambayes_score: 0.0185798 -> 0.018579822 recipients: + mark.dickinson, gvanrossum, rhettinger, facundobatista, jyasskin
2008-01-10 03:51:17	mark.dickinson	set	spambayes_score: 0.0185798 -> 0.0185798 messageid: <[email protected]>
2008-01-10 03:51:15	mark.dickinson	link	issue1682 messages
2008-01-10 03:51:14	mark.dickinson	create