Question

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:

# Revised to show variance in regex and related action.
data, foo, bar = [], nil, nil
input_lines.each do |line|
  if line =~ /Foo(\d+)/
    foo = $1.to_i
  elsif line =~ /Bar=(.*)$/
    bar = $1
  elsif bar
    data.push(line.to_f)
  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?

Answer 1

Paul McGuire’s solution of using an intermediate class REMatcher which performs the match, stores the match group, and returns a boolean for success/fail turned out to produce the most legible code for this purpose.