CODEWITHSUNDEEP
rubyfor-loopiterator
sawa
sawa

Reputation: 168101

Usage of for loop?

Most of the time when I see a for loop used in Ruby, the person who wrote it does not know Ruby well. Usually, it is much more readable when a for loop is replaced by an iterator taking a block such as each.

Is there any use-case where for cannot be easily rewritten by an iterator with a block, or there is an advantage in using for?

Is it true that for is faster than an iterator method because for is a keyword? What is the purpose of for?

Upvotes: 3

Views: 101

Answers (2)

Kirti Thorat
Kirti Thorat

Reputation: 53038

The block syntax is generally preferred by Ruby community.

There is a small difference in variable scope while using for or each. Variable declared within a for loop will be available outside the loop, where as those within an each block are local to the block and will not be available outside it.

Upvotes: 3

spickermann
spickermann

Reputation: 106882

I saw the for loop a lot in Rails books 6-8 years before. But is not preferred anymore.

There is a difference in the scope of the iterator variable. Take the following example:

numbers = [1, 2, 3]

numbers.each do |n|
  # do nothing
end
begin
  puts n 
rescue Exception => e
  puts e.message
end

for n in numbers do 
  # do nothing
end
puts "still: #{n}"

That would have this output:

# undefined local variable or method `n' for main:Object
# still: 3

Upvotes: 4

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