_outline.html.md

From Rails Recipes

From rails recipe, #1: To model rich many-to-many relationships in Rails, use join models to leverage

Active Record's has_many :through() macro.

Macros and the Ruby metaprogramming model

Various approaches

• Substitution

• REXX

• M4

• CPP - Allows (eponymous) preprocessing of C and C++ code relieving the burden on compiler and linker. CPP trades compile time substitution for run time elimination of function calls. Example: min and max are may be implemented as macros in C and C++. CPP can be used for general-purpose string substitution in any text file; it is not limited to C programming language source files.

• TeX - Textual replacement eliminates commonly patterns, and allows parameterization of structurally repetitive but non-identical construction.

• Gema

• Lua macros

• Rewriting - substitution - syntax-based macros

• Macros which operate on parse trees rather than strings.

• Parse trees as inputs, parse trees as outputs.

• Delayed evaluation; call-by-name.

• Methods which run at parse time, instead of at run time.

• Because macro are methods, they are Turing complete and have the full power of Ruby methods.

• Because macros are evaluated at parse time, they do not have access to the "full" Ruby system.

• Helps keep things DRY which isn't methods, classes etc.

Important background

• Paul Graham

• Mirah Language macros

• Scheme?

Ruby macro implementations

Caleb

• Ruby Macros

• Arc macros about 3/4 down page.

Reg Braithewaite

• Macros, Hygiene, and Call By Name in Ruby
• Rewrite
• This is an insanely great talk: Reg on Programming.

Ola Bini

• 3 Ways to Add Ruby Macros

Coding horror