Feature #11151: Numeric#positive? and Numeric#negative?

• Status: Closed
• Assignee: matz (Yukihiro Matsumoto)
• Target version: -

[rafaelfranca (Rafael França)]

We just added Interger#positive? and Interger#negative? to Active Support.

I was wondering if we could get that implemented in Ruby itself and searched if it was already requested before to Ruby code.

I found that it was requested in #5513, but rejected. Since they were requested with more methods, and I don't know Japanese enough to see if there are technical reasons, I thought to request just these two methods again.

The implementation would be something like:

def positive?
  self > 0
end

def negative?
  self < 0
end

And one of its use case is filtering, like:

bunch_of_numbers.select(&:positive?)

If this feature is accepted I can work in a patch.

Related #5513

[usa (Usaku NAKAMURA)]

In #5113, matz said

• We can use > 0 and < 0 for the purpose.
• Complex is Numeric, but we cannot define positive? and negative? for it.

The latter is just appropriate comment, I think.

[rafaelfranca (Rafael França)]

Right. Thank you for the explanation.

So maybe just to Fixnum and Float?

[phluid61 (Matthew Kerwin)]

On 14/05/2015, [e-mail] [e-mail] wrote:

Issue #11151 has been updated by Rafael França.

Right. Thank you for the explanation.

So maybe just to Fixnum and Float?

You probably mean Integer and Float. And possibly also Rational.

That, or add it to Numeric and have it raise in Complex.

--
Matthew Kerwin
http://matthew.kerwin.net.au/

[rafaelfranca (Rafael França)]

You probably mean Integer and Float. And possibly also Rational.

Yeah.

For what I could see, probably we'll just need to publish two functions that we are already using internally. https://github.com/ruby/ruby/blob/d77f4934f8ede19d8a97d4bc748c92e9b8883133/numeric.c#L166 and https://github.com/ruby/ruby/blob/d77f4934f8ede19d8a97d4bc748c92e9b8883133/numeric.c#L182

[matz (Yukihiro Matsumoto)]

Realistic use-case is written. Accepted.
But it should recognize complex numbers (should raise exception).

Matz.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset r50522.

---

numeric.c: Numeric#positive? and Numeric#negative?

• numeric.c (num_positive_p, num_negative_p): add methods
  Numeric#positive? and Numeric#negative?.
  [ruby-core:69173] [Feature #11151]
• numeric.c (flo_positive_p, flo_negative_p): specialiazed
  functions for Float.
• complex.c (Init_Complex): Complex do not have positive? and
  negative? methods