Trying to understand an else clause without preceding conditional - ruby

Question

This code from Handle Web Requests with Ruby appears in the video demo and runs in the video, but I don't see how it could work. The cookie_parts "block" ends with an else clause that has no preceding if or rescue.
require 'socket'
server = TCPServer.new 8000
PAGES = {
"/" => "Hi, welcome to the home page!",
"/about" => "About us: we are http hackers",
"/news" => "We haven't made much news yet with this server, but stay tuned"
}
PAGE_NOT_FOUND = "Sorry, there's nothing here."
loop do
session = server.accept
request = []
while (line = session.gets) && (line.chomp.length > 0)
request << line.chomp
end
puts "finished reading"
http_method, path, protocol = request[0].split(' ') # 3 parts to request line
cookie_header = request.detect { |line| line =~ /^Cookie: / }
cookie_parts = cookie_header.sub /^Cookie: /, ''
cookie_parts = cookie_parts.split('; ')
cookie_parts = cookie_parts.map { |cookie| cookie.split('=') }
cookies = Hash[*cookie_parts.flatten]
else
cookies = {}
end
cookies["session_key"] ||= Time.now.to_f
# nil.to_i returns 0, so if cookie isn't set, count will be 0
count = cookies["session_count"].to_i
count += 1
cookies["session_count"] = count
if PAGES.keys.include?(path)
status = "200 OK"
response_body = PAGES[path]
else
status = "404 Not Found"
response_body = PAGE_NOT_FOUND
end
session.puts <<-HEREDOC
HTTP/1.1 #{status}
set-cookie:session_key=#{cookies["session_key"]}
set-cookie:session_count=#{cookies["session_count"]}
#{response_body}
This was visit number #{cookies["session_count"]}!
HEREDOC
session.close
end
Running the same code locally yields the errors I'd expect:
server.rb:28: else without rescue is useless
server.rb:57: syntax error, unexpected `end', expecting end-of-input
What conditional or block is the else supposed to belong to?

Answer 1

Watch the rest of the video, to wit, at ~5:30 you'll see the missing if I mentioned in my comment:
if cookie_header = request.detect { |line| line =~ /^Cookie: / }
cookie_parts = cookie_header.sub /^Cookie: /, ''
cookie_parts = cookie_parts.split('; ')
cookie_parts = cookie_parts.map { |cookie| cookie.split('=') }
cookies = Hash[*cookie_parts.flatten]
else
cookies = {}
end

Answer 2

In the middle of the code in your question, there is this section
cookie_header = request.detect { |line| line =~ /^Cookie: / }
cookie_parts = cookie_header.sub /^Cookie: /, ''
cookie_parts = cookie_parts.split('; ')
cookie_parts = cookie_parts.map { |cookie| cookie.split('=') }
cookies = Hash[*cookie_parts.flatten]
else
cookies = {}
end
There you have an else block but there is no if condition in front of it. Ruby doesn't know how to handle it and therefore the error message.
I agree that the error message is a bit misleading because an else block like that is more likely missing an if condition than a rescue. But a rescue block is also an example in which Ruby allows an else like this:
begin
# code that might raise an error
rescue
# code that is run when there was an error
else
# code that is run when there was _no_ error
end