From: Kyle <kcy5b@...>
Date: 2009-11-16T02:32:01+09:00
Subject: Re: Traversing the contents of a proc (for a DSL)

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Generally - no. A proc is compiled code, it doesn't remember its own source 
code. There are libraries that provide some deeper introspection tools -- like 
the ParseTree / Ruby2Ruby libraries. Also, there are several DSLs very simllar 
to what you're talking about already -- check out Markaby: 

http://markaby.rubyforge.org/

 

On Sunday November 15 2009 3:58:08 am Siemen Baader wrote:
> Hi List,
>
> Is it possible to traverse and modify the statements inside a Proc
> after it has been created?
>
> I'm playing with a small DSL for HTML, which should look like this.
>
> html {
>   head { title {"Hello World"} }
>   body {
>     h1 { "hello"}
>     p {
>      "text body"
>      "more text"
>     }
>   }
> }
>
> If it is possible to recursively traverse through the statements in
> each block, I could join the lines together with the + operator, and
> the implementation would be fairly easy - just recursive calls that
> return text. But it does not look like this is possible...
>
> An alternative would be to create a new object for each node in the
> HTML (eg body or h1), and let each method call inside this node assign
> its content to an array there. Less functional style and more
> overhead, but doable. But this requires either that I catch the
> creation of new strings (no idea if that is possible) for them to be
> added to the node as well, or that I introduce a new method to create
> strings.
>
> Any comments highly appreciated!
>
> cheers,
> Siemen


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