不同机器上红宝石中不同的“ upto”行为（“ upto”：未指定任何块（LocalJumpError））

Question

This code works on one machine but not the other:

puts 1.upto(5)

On the working machine, the code returns '#'.

On the other machine, I get this error:

test.rb:1:in `upto': no block given (LocalJumpError) from test.rb:1

Both machines have rails 2.2.2. The machine where this code works has ruby 1.8.7, while the two machines where this code doesn't work have ruby 1.8.6 and ruby 1.8.7 enterprise edition respectively.

Answer 1

Yes turns out in ruby 1.8.6 upto requires a block, while 1.8.7 a block is not necessary.

So solution is either to upgrade to 1.8.7 or use a block or do 1...4.to_a.

Answer 2

To get the 1.8.7+ behaviour in 1.8.6 you can do:

require 'enumerator'
1.enum_for(:upto, 5)

Which works the same on all versions and is functionally equivalent to 1.upto(5) without block in 1.8.7+ (though a little more verbose).

Though in this specific case you can of course just use a range.