On: What I didn’t know about Ruby Numbers

[pqdbr]

Ruby 2.7.2, just fire up irb:

BigDecimal("123.45") == 123.45.to_d

=> true

[gioele → pqdbr]

That is just a coincidence (decimal ending in "5"), plus the fact that `.to_d` does some cleanup preprocessing.

Counterexample:

  BigDecimal("1.5999999999999996") == 1.5999999999999996.to_d
  => false

The most ergonomic way to initialize decimal numbers is IMO

  "123.45".to_d

(Note the quotes around the number. `.to_d` is being called on a string.)

BigDecimal's only lossless API is through strings. It would be nice to have native support for decimals at the parser level:

  0d123.45 => BigDecimal("123.45")

[edflsafoiewq → pqdbr]

Shows you what I know. I thought I had tested this. I guess it keeps only a certain amount of precision.