## Feature #12039

### Fixnum#infinite?/Bignum#infinite or Numeric#infinte, consistent with Float#infinite? and BigDecimal#infinite?

Added by ioquatix (Samuel Williams) almost 5 years ago.
Updated about 4 years ago.

**Description**

We have an issue where it is not easy to ask if a number is +ve or -ve infinity. https://github.com/rails/arel/issues/411

Both Float and BigDecimal do respond to infinite? but Integer derivatives don't. It sort of makes sense, since we don't have an infinity value for Fixnum/Bignum. However, it makes polymorphic code hard.

[13] pry(main)> Float::INFINITY.infinite?
=> 1
[14] pry(main)> -Float::INFINITY.infinite?
=> -1
[15] pry(main)> BigDecimal::INFINITY.infinite?
=> 1
[16] pry(main)> -BigDecimal::INFINITY.infinite?
=> -1

Given a Numeric value x, it would be nice to query if it is INFINITY or not. Propose adding a default implementation to Numeric, which always returns false or nil.

It might also make sense to consider if other "predicates" make sense, e.g. `nan?`

They should be declared on Numeric with a default logical implementation where possible.

This is probably a useful method to be able to rely on universally, even if `Fixnum`

and `Bignum`

just return `false`

.

Another real-world use-case where I found Numeric#infinite? useful is JSON validation. Infinities are not allowed in JSON so a programmer want to filter them out before converting a Numeric into JSON, but that is not straight-forward right now. With this method it becomes much OO-ish.

Agreed. Add #finite? and #infinite?

Matz.

**Tracker** changed from *Bug* to *Feature*

What behavior is desirable for a Complex?

I think the following definition is acceptable for a Complex:

```
def inifinite?
self.magnitude.infinite?
end
```

This looks good, do you think we can integrate this at some point? What do we need to do?

**Assignee** set to *mrkn (Kenta Murata)*

**Status** changed from *Open* to *Closed*

Applied in changeset r55702.

numeric.c, complex.c: Add finite? and infinite? consistent with Float

numeric.c (num_finite_p, num_infinite_p): Add Numeric#finite? and

Numeric#infinite? [Feature #12039] [ruby-core:73618]

complex.c (rb_complex_finite_p): Add Complex#finite?

complex.c (rb_complex_infinite_p): Add Complex#infinite?

test/ruby/test_bignum.rb: Add test for Integer#finite? and

Integer#infinite?

test/ruby/test_fixnum.rb: ditto.

test/ruby/test_rational.rb: Add test for Rational#finite? and

Rational#infinite?

test/ruby/test_complex.rb: Add test for Complex#finite? and

Complex#infinite?

Thank you for your hard work :)

**Related to** *Feature #10641: Introduce Fixnum#finite? and Bignum#finite?* added

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