From: Ryan Davis <ryand-ruby@...>
Date: 2010-12-20T19:40:31+09:00
Subject: Re: How to implement such a Domain-Specific-Language (DSL)?


On Dec 20, 2010, at 01:18 , Zd Yu wrote:

> "Jesús Gabriel y Galán" <jgabrielygalan@gmail.com> wrote in post 
> #969520:
>> you can do that easily with method_missing
> 
> Thanks. it looks like a promising solution. but I have two more 
> requirements:
> 
> 1. what if the event name includes a dot '.'?

You have two event names and you need to clarify: the key in the hash, or the "variable" used in the DSL?

If the former, you probably want to munge the names as they come in.

If the latter, you probably want to munge what you wind up instance eval'ing.

If neither, you're probably doing it as a scoping mechanism of some sort and you probably need to build a hierarchy in @events and change method missing to do a proper hierarchical lookup (probably recursively, passing down to subsequent sub-EventData's).

> 2. I also want the left value of the equation (metric_A in the example) 
> to be added into the Hash, because it is possible that a new metric 
> needs to be calculated based on the existing metric.

Then chuck the hash entirely and use local variables. This will probably collide with the above suggestion for namespacing... so munging the input script is a better route.