Re: [Opencxx-users] future directions

[Stefan S. <se...@sy...>]

Hi Brian,

Brian Kahne wrote:

> One feature that would be really nice (perhaps this is possible- please 
> let me know if it is!) would be to get the type of an arbitrary 
> expression.  For example, if I wanted to implement a "let" block, e.g.
> 
>     let (i = <expr>, j = <expr>) {
> 
>     }
> 
> it would be really nice if I could directly query the ptree object 
> storing <expr> for its return type so that I could transform this code 
> into normal C++ declarations.

yes, that would be possible with typed ptree nodes, as then the 'Walker'
classes would not only act as a traversal, but also as a visitor, i.e.
one could use the double-dispatch mechanism to resolve the type that
is part of of ptree nodes being traversed.
Right now the parent ptree node has to detect the sub-node's type
by inspecting the node's topology, i.e. instead of

if (node->Car()->IsLeaf()) do_something();

one would write

if (if_statement->else_block)
   // access the *typed* 'else' statement, as 'this'
   // is a visitor with various 'visit_statement(Statement *)' methods
   if_statement->else_block->accept(this);

You get the idea...

> I think that releasing the code as a library would be very helpful, but 
> keeping the occ executable would still be a good idea- it's a very 
> convenient way to use the tool.

I agree. As a convenience tool it covers the majority of the use cases,
so it surely has its use.

Regards,
		Stefan