Bug #16395: .any? and .all? methods, flawed.

• Status: Rejected
• Assignee: -
• Target version: -
• ruby -v: 2.6.5
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN

[stiuna (Juan Gregorio)]

The dynamics of the script is simple, no explanations needed, look for yourselves:

#                 100E1       312A3 8B64  282F   C4A  B28F 
result = '99E2E403100E1A685A63312A308B6478282F2B2C4A34B28F7E'
virus = ['100E1', '312A3', '8B64', '282F', 'C4A', 'B28F']

count = 0
virus.all? {|i|
    puts i
    if result.include? i
        count += 1
    end
}

puts "Coincidences: #{count}"

Out:

100E1
312A3
8B64
282F
C4A
B28F
Coincidences: 6

That's correct. Now change .all? for .any?

Out:

100E1
Coincidences: 1

That's not right. Now let's modify the .any? block like this:

virus.any? {|i|
    if result.include? i
        count += 1
        puts "#{count}:#{i}"
    end
}

Out:

1:100E1
2:312A3
3:8B64
4:282F
5:C4A
6:B28F
Coincidences: 6

That's correct. Now change .any? for .all?

Out:

1:100E1
Coincidences: 1

That's not right. Now let's modify the .all? block like this:

virus.all? {|i|
    if result.include? i
        puts "#{count}:#{i}"
        count += 1
    end
}

Out:

0:100E1
1:312A3
2:8B64
3:282F
4:C4A
5:B28F
Coincidences: 6

That's correct. If you look only I have changed the order of the instructions puts and count.

In case you don't understand me, I'll put the complete code with each method:

result = '99E2E403100E1A685A63312A308B6478282F2B2C4A34B28F7E'
virus = ['100E1', '312A3', '8B64', '282F', 'C4A', 'B28F']

count = 0
virus.any? {|i|
    if result.include? i
        # If these two lines change order the program fails.
        count += 1
        puts "#{count}:#{i}"
    end
}

puts "Coincidences: #{count}"

The output will print 6 coincidences, but if you change the order of the instructions puts and count the program returns 1 coincidence.

Now with .all?

result = '99E2E403100E1A685A63312A308B6478282F2B2C4A34B28F7E'
virus = ['100E1', '312A3', '8B64', '282F', 'C4A', 'B28F']

count = 0
virus.all? {|i|
    if result.include? i
        # If these two lines change order the program fails. Compare the order with .any?
        puts "#{count}:#{i}"
        count += 1
    end
}

puts "Coincidences: #{count}"

The output will print 6 coincidences, but if you change the order of the instructions puts and count the program returns 1 coincidence.

[Hanmac (Hans Mackowiak)]

your problem is that .any? and .all? wants a value returned for the block which is truly or falsely

puts returns nil which is falsely, in the second example count += 1 returns an integer which is truly

EDIT: it looks like you might want to check out virus.count { |i| result.include? i } ?

[mame (Yusuke Endoh)]

• Status changed from Open to Rejected

@Hanmac (Hans Mackowiak) is right.

ary = [1, 2, 3, 4, 5]

result = ary.any? {|n| p n; n == 3 } #=> 1, 2, 3
p result #=> true

result = ary.all? {|n| p n; n != 3 } #=> 1, 2, 3
p result #=> false

You may want to use each instead of any? and all?, I guess.

[shevegen (Robert A. Heiler)]

The dynamics of the script is simple, no explanations needed, look for yourselves:

I do not think that this can be a useful issue description because there may be
secondary aspect to consider for when requesting changes, including backwards
compatibility after a given change/suggestion. So even if there were a problem in
regards to the behaviour, it would be better to include these considerations in the
issue tracker, even if you think that any behaviour is flawed or not optimal.

If you work with .any? .select and .reject, I personally found it better to split
up the tasks, finish working on the dataset, and then do a separate reporting. Right
now you combine both in one go, which can lead to the confusion you described.