## Feature #12039

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

**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.

**Related issues**

### Associated revisions

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]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?

### History

#### #1 [ruby-core:73619] Updated by ioquatix (Samuel Williams) almost 2 years ago

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.

#### #2 [ruby-core:73622] Updated by seantheprogrammer (Sean Griffin) almost 2 years ago

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

and `Bignum`

just return `false`

.

#### #3 [ruby-core:73917] Updated by shyouhei (Shyouhei Urabe) almost 2 years ago

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.

#### #4 [ruby-core:74365] Updated by matz (Yukihiro Matsumoto) almost 2 years ago

Agreed. Add #finite? and #infinite?

Matz.

#### #5 [ruby-core:74367] Updated by nobu (Nobuyoshi Nakada) almost 2 years ago

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

#### #6 [ruby-core:74458] Updated by mrkn (Kenta Murata) almost 2 years ago

What behavior is desirable for a Complex?

#### #7 [ruby-core:74459] Updated by mrkn (Kenta Murata) almost 2 years ago

I think the following definition is acceptable for a Complex:

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

#### #8 [ruby-core:75850] Updated by ioquatix (Samuel Williams) over 1 year ago

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

#### #9 [ruby-core:76286] Updated by mrkn (Kenta Murata) over 1 year ago

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

#### #10 Updated by mrkn (Kenta Murata) over 1 year ago

**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]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?

#### #11 [ruby-core:77470] Updated by ioquatix (Samuel Williams) about 1 year ago

Thank you for your hard work :)

#### #12 Updated by shyouhei (Shyouhei Urabe) 12 months ago

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

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]

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?