ruby gotcha

gotcha.rb

# We all know about this Python gotcha:
# def foo(x=[]):
#     x.append(1)
#     return len(x)
# But the answer is not to do what ruby does.
# Would you expect this to run quickly or slowly?


def runonce
  urls = ["yahoo.com", "google.com", "bing.com", "marxists.org"]
  urls.map { |url|
    contents = `curl -L #{url}`
    contents.encode('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '').split("\n").sample
  }
end

def foo(lines = runonce())
  lines.sample
end

foo()
foo()
foo()