From: Eric Hodel <drbrain@...7.net>
Date: 2004-11-11T03:43:27+09:00
Subject: Re: Ruby code generation: string vs. AST based (2.0 or beyond)

On Nov 9, 2004, at 10:43 PM, itsme213 wrote:

> Code generation in ruby is great.
>
> The only thing I find is that, since it is essentially all string
> manipulation prior to eval, none of it is executable (or testable!) 
> until it
> is eval'd. So I find myself writing straight code, testing it, then 
> mentally
> abstracting out the string patterns in that code, then using those in 
> my
> code generation.
>
> Reading those string patterns more than a day later makes my brain 
> hurt.
>
> What are the chances, somewhere in or beyond 2.0, of code generation 
> being
> based on something more like the following:
>  - write and test executable code
>  - get access to an AST of that code itself
>  - implement code generation by cloning/modifying the AST clone

Not released just yet, but using ParseTree (a soon to be released 
RubyForge project), Ryan Davis and myself are working on a something 
similar.  We have loads of cool tools to help us munge the AST to do 
horrible things.

(If you've been hanging out on #ruby-lang, you probably know what that 
project is.)

> This would require a published AST, some manipulations on it, and an 
> eval
> that takes ASTs.

Well, you could probably emit Ruby code instead from the modified AST 
instead, then run the munged Ruby code through the interpreter in a 
second stage...