How I learned to stop worrying and love macros
summary
Explains exactly how Elixir macros generate real code: use of __using__ to inject functions, quote/unquote and unquote_splicing to build AST, and before_compile plus module attributes to collect rules then emit final functions. Shows decoding generated bytecode from Gettext to inspect the compiled functions, compares macro generation with EEx template codegen, and demos a firewall DSL that compiles CIDR/range rules into pattern-matched functions. Advises sparing use, notes macros speed runtime and reduce duplication but can obscure debugging.
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chapters (13)
- 0:00Introduction to macros
- 1:21Why use meta programming
- 5:23Macros and code generation
- 12:37Using macros in practice
- 17:37Detecting and defining functions
- 23:29Before compile hooks
- 26:19Overusing macros
- 28:04Code generation with EEx
- 29:30Debugging generated code
- 36:07Splitting implementations across files
- 39:40Macros and maintenance
- 44:20DSLs with macros
- 56:51Wrap up and resources
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