dos_and_donts.md

Regular expression strategies

Know what regular expressions (regexes) are good for, and what they don't do well at all.

Use regexes for:

• Matching text against a pattern
• Substituting strings when they match a pattern (find and replace)
• Validating attributes against a pattern
  • The best way to validate an email address beyond idiot-checking is to send mail to it and confirm receipt.
• Parsing data such as log files with defined delimiters or separators. Some exceptions are listed below.

Do not use regexes for:

• Parsing markup such as XML (HTML). Use Nokogiri.
• Parsing serialization formats such as JSON or YAML. Use JSON or Psych/YAML.
• Parsing URI's. Use URI and have a look at its regular expressions
• Parsing comma-separated values (CSV). Use CSV.