Regular expressions that work "everywhere"
The article discusses the challenge of writing regular expressions that work consistently across different programming languages and regex engines. It highlights subtle differences in syntax and behavior between common implementations, such as those in Perl, Python, and JavaScript, and offers strategies for writing more portable regex patterns.
Background
- **Regular expressions (regex)** are patterns used to search, match, and manipulate text — a core tool in programming, text editing, and data cleaning.
- Although regex syntax looks similar across languages (Python, JavaScript, grep, sed, etc.), different implementations have subtle incompatibilities in features, escape rules, and behavior.
- The blog post introduces **"regex that works everywhere"** — a practical, portable subset of regex syntax safe to use across many common tools without unexpected failures.
- This matters because developers often copy-paste regex between environments (e.g., from a web form validator into a shell script) only to find it breaks due to engine differences.
- John D. Cook is a well-known applied mathematician and blogger who frequently writes about math, programming, and the quirks of technical tools.