Dir.glob with sort issue - ruby-on-rails

Question

As in "Alphabetize results of Dir.glob", I use sort to get file list in alphabetical order:
Dir.glob("#{options[:path]}/**/*.jpg", File::FNM_CASEFOLD).sort { |file|
dir, filename = file.match(/.+\/(.+)\/(.+)/).captures
# ---cut---
}
Without the sort it works good, but with it fails with error:
$ rake slides:import -- --user foo --path /bar/baz
(in /home/user/app_folder)
"baz/ - /bar/baz/DSC_4120.JPG - saved"
rake aborted!
ArgumentError: comparison of String with 0 failed
/home/footoo/footoo/lib/tasks/slides.rake:41:in `>'
/home/footoo/footoo/lib/tasks/slides.rake:41:in `sort'
/home/footoo/footoo/lib/tasks/slides.rake:41:in `block (2 levels) in <top (required)>'
/usr/local/rvm/gems/ruby-2.1.5/bin/ruby_executable_hooks:15:in `eval'
/usr/local/rvm/gems/ruby-2.1.5/bin/ruby_executable_hooks:15:in `<main>'
Tasks: TOP => slides:import
Any idea what's wrong ?
Full code available on Github.

Answer 1

When sort is given a block it expects it to return -1,0 or 1 in order to know how to sort (a custom <=> function). You need to add each after sort to get back the default sort and the intended behavior.
Dir.glob("#{options[:path]}/**/*.jpg", File::FNM_CASEFOLD).sort.each{|file|
....
}
Read the documentation here: http://ruby-doc.org/core-2.2.0/Array.html#method-i-sort