From: Christopher Dicely <cmdicely@...>
Date: 2009-04-13T01:58:23+09:00
Subject: Re: a few thoughts for ruby...

On Sat, Apr 11, 2009 at 1:35 PM, Colin Bartlett <colinb2r@googlemail.com> wrote:
>>> Roger Pack
>>>
>>> Thought I'd pass these thoughts by the readers here before sending them
>>> to core.  They're my current wish list :)
>>>
>>> 1) add an Object#in? method to complement the existing Array#include?
>
>> Joel VanderWerf
>>
>> It's not really symmetrical. Array has an #include? method because it is
>> a collection. Object has #in? because it is--what? A potential member of
>> a collection?
>
>> Robert Klemme
>>
>> I don't see the benefit but I'm also not strongly against.  I do see
>> Joel's point about the reversion.  Basically it is strange that every
>> object should be able to answer a question that only the collection can
>> answer.  Plus, you can easily add it yourself if you need it.
>
> Sometimes the best (or better) usage depends on the context.
> For example, on some occasions we use:  Integer === object
> and on other occasions we use:          object.kind_of?( Integer )
> So I'm not against this on principle, and for me the question is
> what is the balance between not adding things unless we need to
> and does this make things easier in a significant number of cases.
> I don't know the answer!
>
>
>>> Roger Pack
>>> 4) (this one's controversial) remove the extra # for code in strings
>>> (i.e. "string#{code}") -> "string{code}" less typing.
>
> I'm not in favour, for Robert Klemme's reasons.
>
>
>>>> Roger Pack
>>>>
>>>> 5) add a BigDecimal(float) method.
>>>>  -> BigDecimal.new("%f" % float)
>
>>> Robert Klemme
>>>
>>> Seems reasonable at first sight but the absence might have a reason.
>>> For example, by making the conversion to String explicit it is more
>>> obvious that float and BigDecimal are not really compatible.
>
>> Roger Pack
>>
>> Yeah I wonder that myself. I was just hoping to make it easier to use
>> BigDecimal, since Floats are so imprecise to use for decimal numbers :)
>
> Then probably best to start with BigDecimal and keep using it?
> We can always use  BD = BigDecimal ; BD.new( "123.456" )
> and I seem to recall that there's a way to assign a method to a variable
> which could reduce this to BD( "123.456" ). I think it's important
> to normally use strings to get BigDecimal values to avoid precision errors.

True, so I'd agree that encouraging Float -> BigDecimal conversions
isn't a great idea. OTOH, what I would like to see is BigDecimal (and
maybe even Rational) literal syntax in Ruby in the future, e.g.

1.23  # Float
1.23d # BigDecimal
a =1 # Fixnum
a/2 # => 0
b = 1r # Rational
b/2 # == Rational("1/2")

Essentially, provide a way to make working with exact numbers
convenient without necessarily adopting all the behavioral changes of
the mathn library (which you may want to avoid in order not to break
older code.)