I'm pretty experienced with Perl and Ruby but new to Python so I'm hoping someone can show me the Pythonic way to accomplish the following task. I want to compare several lines against multiple regular expressions and retrieve the matching group. In Ruby it would be something like this:

STDIN.each_line do |line|
  case line
    when /^A:(.*?)$/ then puts "FOO: #{$1}"
    when /^B:(.*?)$/ then puts "BAR: #{$1}"
    # when ...
    else puts "NO MATCH: #{line}"
  end
end

My attempts in Python are turning out pretty ugly because the matching group is returned from a call to match/search on a regular expression and Python has no assignment in conditionals or switch statements. What's the Pythonic way to do (or think!) about this problem?