如何覆盖Ruby Ranges的..和…运算符以接受Float :: INFINITY？

Question

I want to override the .. and ... operators in Ruby's Range .

Reason is, I'm working with infinite date ranges in the database. If you pull an infinty datetime out of Postgres, you get a Float::INFINITY in Ruby.

The problem with this is, I cannot use Float::INFINITY as the end of a range:

Date.today...Float::INFINITY
=> Wed, 02 Nov 2016...Infinity 

DateTime.now...Float::INFINITY
# ArgumentError: bad value for range

Time.now...Float::INFINITY
# ArgumentError: bad value for range

... yet I use .. and ... syntax quite often in my code.

To even be able to construct the range, you need to use DateTime::Infinity.new instead:

Date.today...DateTime::Infinity.new
=> Wed, 02 Nov 2016...#<Date::Infinity:0x007fd82348c698 @d=1> 

DateTime.now...DateTime::Infinity.new
=> Wed, 02 Nov 2016 12:57:07 +0000...#<Date::Infinity:0x007fd82348c698 @d=1> 

Time.now...DateTime::Infinity.new
=> 2016-11-02 12:57:33 +0000...#<Date::Infinity:0x007fd82348c698 @d=1> 

But I would need to do the the Float::INFINITY -> DateTime::Infinity.new conversion every time:

model.start_time...convert_infinity(model.end_time)

Is there a way I can override the .. and ... operators so that I can incorporate the conversion function and keep the syntactic sugar?

Answer 1

I don't think that what you want to do is a correct way of solving such issue.

What I would suggest instead, is to simply override the end_date method in model:

def end_date
  super == Float::INFINITY ? DateTime::Infinity.new : super
end

This basically says if end_date in db is Float::INFINITY return DateTime::Infinity.new as end_date , otherwise return what's in database.

Answer 2

Ruby 2.6 introduces endless range , which can be used in this manner, for example:

(DateTime.now..)
(DateTime.now...)

This provides a new approach to answering this question. Hope it's useful for someone!