compile-time access to parsed code

[janderson]

Hasan Aljudy wrote:
> alot of ideas for DSL that are coming up are really just additions of 
> feature to already existing concepts in D.
> 
> For example, mapping a DB table/row to a D class/object.
> One would probably do something like:
> mixin( Model!(
>    "Person:
>      char[100] name;
>      int       age;
>      ForeignKey(Car)  car;
>    "
> ))
> 
> and then one would have to write a parser for that, which will 
> essentially produce a regular D class, with the same attributes, plus 
> some additional magic:
> 

In this case all the parser would do is find Token: and re-write it as 
"class Person"  Then find ( and replace it with !(.  Finally it would 
append the magic on the end.  I hope we will eventually get lots of 
library functions to help this process out.

This essentially makes the reuseable part easy to write at a cost of 
spending a little time writing the Model! library.

In some respects I agree, when I originally posted an idea like this a 
few years ago, one of my suggestions asked to have access to D's 
symbolic tree passed into the template.

-Joel