From: "Thomas Søndergaard" <thomass@...>
Date: 2002-08-11T22:47:56+09:00
Subject: Re: empty file returns nil not empty string?

Sure - here's a test case:

require 'test/unit'

class TestFileRead < Test::Unit::TestCase
  def test_read_empty
    `touch empty.txt`
    assert_equal(0, File.size("empty.txt"))
    File.open("empty.txt") {
      |f|
      assert_equal("", f.read)
      assert_equal(nil, f.read)
    }
  end
end

Here's the output
===========================
$ /C/ruby167/bin/ruby readtest.rb
Loaded suite readtest
Started...
..
Finished in 0.13 seconds.
1 runs, 3 assertions, 0 failures, 0 errors
===========================
$ /C/ruby172/bin/ruby readtest.rb
c:/ruby172/lib/ruby/site_ruby/1.7/test/unit/error.rb:35: warning: escaped
terminator '"' inside string interpolation
Loaded suite readtest
Started...
..
Failure occurred in test_read_empty(TestFileRead) [readtest.rb:12]: Expected
<> but was <nil>

Finished in 0.02 seconds.
1 runs, 2 assertions, 1 failures, 0 errors
===========================

Cheers,

Thomas

> >>>>> "T" == =?iso-8859-1?Q?Thomas S=F8ndergaard?= <iso-8859-1> writes:
>
> T> In ruby-1.6.7 reading an empty file returns an empty string before
returning
> T> nil. 1.7.2 doesn't do that - why?
>
>  Can you give an example ?
>
> pigeon% ls -al aa
> -rw-r--r--    1 ts       ts              0 Aug 11 15:06 aa
> pigeon%
>
> pigeon% ruby -ve 'a = File.open("aa"); while b = a.gets; p b; end'
> ruby 1.6.7 (2002-03-01) [i686-linux]
> pigeon%
>
>
> Guy Decoux
>