From: gabriele renzi <surrender_it@...>
Date: 2006-01-04T04:22:58+09:00
Subject: Re: DSL help?

Ezra Zygmuntowicz ha scritto:
> Hey rubyists-
> 
>     I was wondering if someone could help me make this small dsl I 
> wrote  into a little bit better syntax. The Cond class just takes a 
> block in  its constructor and converts what's inside the block into an 
> sql  where clause with ? syntax like this:
> 
> c = Cond.new do
>   first_name ‘=’, ‘Ezra’
>   start_date ‘between’, ‘2006-01-01′, ‘2006-01-30′
>   last_name ‘like’, ‘Zyg%’
>   sql ‘hosts.id = something.id'
> end
> 
> p c.where
> #=> ["first_name = ? and start_date between ? and ? and last_name  LIKE 
> ? and hosts.id = something.id", "Ezra", "2006-01-01",  "2006-01-30", 
> "Zyg%"]
> 
>     I would like to be able to get rid of the quotes around the  
> operators '=', '<=', 'LIKE' and so on to become =, <= and LIKE . Also  I 
> would like to be able to get rid of the need for commas inside the  
> block as well. Inside of the Cond class initialize method it justs  uses 
> instance_eval &block to get the block contents and then uses  
> method_missing to build a nested array for each statement.

look on RAA for the "Criteria" package, you may find it interesting and 
a moe tested than your own. At least you can fish in it for good ideas 
if you don't want to use it :)