Feature #12612: Switch Range#=== to use cover? instead of include?

• Status: Rejected
• Assignee: -
• Target version: -

[zverok (Victor Shepelev)]

Currently, Range#=== is an alias of #include?, which works by #each-ing all the values and comparing them to the checked value. It may lead to fascinating inefficiencies, when working with strings or other similar classes (for example, IP class for allowing/disallowing IP ranges). Moreover, it is not consistent with behavior of numerical ranges (which is kinda special case, I guess):

(1...3) === 2.5 # true - though (1..3).to_a.include?(2.5) is false
('a'...'z') === 'foo' # false - because ('a'..'z').to_a.include?('foo') is false

As === is heavily used in case and grep, and there is no option to replace it manually with cover? there, maybe it would be reasonable to change the behavior?

To be honest, I could imagine no real cases when include? is preferable for identity check.

[zverok (Victor Shepelev)]

Did anybody saw this?..

[matz (Yukihiro Matsumoto)]

• Status changed from Open to Rejected

I see no real-world use-case for Range#=== with strings.
Besides that, using cover? behavior for string ranges would introduce incompatibility.

Matz.

[zverok (Victor Shepelev)]

I encountered the problem in production code, it was not strings, but specialized IPAddress class, to filter "if IP is in range" -- it was SUDDENLY 0.4 sec on each request to server spent just to (IPAddress.new(from)..IPAddress.new(to)).to_a in "innocently" looking:

case ip
when admin_ip_range
...

Another real cases:

• ranges of Dates/Times/DateTimes
• Measure units (like https://github.com/joshwlewis/unitwise)
• Any other specialized enumerable AND comparable value class

Yes, proposed behavior is incompatible with current, but I am not sure it is a bad thing:

(Date.parse('2016-05-01')..Date.today) === DateTime.parse('2016-06-01 12:30')
# => false 
(Date.parse('2016-05-01')..Date.today).cover?(DateTime.parse('2016-06-01 12:30'))
# => true 

# Which is more logical? What you'll intuitively expect here:
case DateTime.parse('2016-06-01 12:30')
when Date.parse('2016-05-01')..Date.today
  # looks like we SHOULD be here, but... 

[shyouhei (Shyouhei Urabe)]

• Related to Feature #12996: Optimize Range#=== added

[matz (Yukihiro Matsumoto)]

• Related to Feature #14575: Switch Range#=== to use cover? instead of include? added

[matz (Yukihiro Matsumoto)]

• Related to deleted (Feature #14575: Switch Range#=== to use cover? instead of include?)

[matz (Yukihiro Matsumoto)]

• Has duplicate Feature #14575: Switch Range#=== to use cover? instead of include? added