Discussion on: How do you regex?

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For tools, I like to use Ruby to write my regex. I often refer to the documentation. I invariably pair the regex with lots of local tests.

Below is a basic test. I save the code to a file (e.g. regexp.rb) and then run ruby regexp.rb.

THE_REGEX = %r{\d+}
def the_matcher(text)
  THE_REGEX.match?(text)
end

if __FILE__ == $0
  [
    ["123", true],
    ["abc", false],
  ].each do |text, expected|
    actual = the_matcher(text)
    if actual == expected
      puts "SUCCESS: for #the_matcher(#{text.inspect})"
    else
      puts "FAILURE: Expected #the_matcher(#{text.inspect}) to return #{expected}, got #{actual}"
    end
  end
end

I favor these basic tests as I'm writing regular expressions as they are super fast to run. And are easy to later port into the test suite of the application (which depending on how the application tests are constructed might be faster or slower to run).

For types of problems, I've used it for:

Creating a command line REPL for facilitating note taking/random tables in RPGs.
For tidying up my text before writing a Forem Pull Requests
For parsing/tokenizing strings
For pruning my local git branchs when the upstream tracking branch goes away.
For building a stats task for lines of code in an application