Daryoush Mehrtash wrote:
I am trying to understand Domain Specific Language implementation in Ruby,
there are lot of examples such as
http://www.infoq.com/articles/eval-options-in-ruby, but I can't find a
definitive guide on the interpreters rule for evaluating a line of DSL
String in instance_eval call.
DSL is a state of mind, not a language inside a string inside a language.
The state of mind is that you intend to write in one language style,
inside another language. For example, Rake is a _light_ form of rule
solver, so you can write it in a format paralleling a Makefile:
task :rule_1 => [:rule_2, :rule_C] do
To write in a declarative mode, write object methods with store their
commands in an engine, and then process the engine. Here's a little
Flea script to draw a spiral:
egg = startOvum(18, 45, 100)
ax = egg.newRootAxiom('A')
b = egg.newAxiom('B')
The commands like longer, right, color, etc are turtle graphics
describing a shape. render then outputs the shape.
All the ActiveRecord association commands - has_many, belongs_to, etc
- qualify as DSLs too. The goal is to give your user-programmer a
clear but deep interface, so they can write the command they need, in
the relevant context they need, and the engine on the inside hides the
http://tinyurl.com/yrc77g <-- assert_latest Model