I've been trying to collect arrays with digits into one array. If I try to use + it returns emty array as output. Using concat returns expected array of digits. How does it work and what the main difference between these Ruby methods?
0.step.with_object([]) do |index, output|
output + [index]
break output if index == 100
do # returns empty array
0.step.with_object([]) do |index, output|
output.concat [index]
break output if index == 100
end # returns an array contains digits from 0 to 100
Unlike Enumerable#reduce, Enumerable#each_with_object passes the same object through reducing process.
Array#+ creates a new instance, leaving the original object unrouched.
Array#concat mutates the original object.
With reduce the result will be the same:
0.step.reduce([]) do |acc, index|
break acc if index > 100
acc + [index]
end