CODEWITHSUNDEEP
ruby
Spencer
Spencer

Reputation: 85

Ruby I/O - File Handle Left Open

Can anyone provide some clues as to why these two pieces of code are not equivalent? My only thought is that the .open in the latter code portion is not in a block and the file handle is left open.

File.open(file) do |io|
  io.each_line do |line|
    body_string << line
  end
end

and this one

File.open(file).each_line {|line| body_string << line}

Thanks.

Upvotes: 1

Views: 1109

Answers (2)

Aidan Cully
Aidan Cully

Reputation: 5507

File test.rb:

def test1
  body_string = []
  [ File.open(ARGV[0]).each_line { |line| body_string << line }, body_string ]
end
def test2
  body_string = []
  [ File.open(ARGV[0]) do |io|
    io.each_line { |line| body_string << line }
  end, body_string ]
end
puts(test1.inspect)
puts(test2.inspect)

File f:

hello!

output of ruby test.rb f:

[#<File:f>, ["hello!\n"]]
[#<File:f (closed)>, ["hello!\n"]]

The only difference is that, when File.open is given a block, it automatically closes the file handle.

HTH

Upvotes: 3

phtrivier
phtrivier

Reputation: 13361

See IO class's API.

If File.open is given a block , it opens the file, executes the block, then closes the file.

If it is not given a block, it returns an object representing the file (just like File::new), so it might still be opened.

Upvotes: 5

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