Re: [Caml-list] ppx_metaquot location passing

[Alain Frisch <alain.frisch@lexifi.com>]

Hi Dmitry,

Looking at the comments in ppx_metaquot.ml, there are two ways to 
achieve that:

   - By default, the location of all created notes is set to the 
expression "!Ast_helper.default_loc".  You can set this reference 
directly or with Ast_helper.with_default_loc.

   - You can change this expression with a @metaloc attribute (typically 
to specify a locally bound variable).


Hope this helps,

Alain



On 02/09/2015 10:23, Dmitry Bely wrote:
> I'm writing a ppx rewriter. It iterates over structure items and for
> some of them generates the new ones. A simplified example:
>
> let defs = ref []
>
> let mapper argv =
>    let expr mapper expr =
>      ...
>    let rec structure mapper li =
>      let li =
>        List.fold_left (fun acc ({pstr_loc = loc} as si) ->
>          let si = default_mapper.structure_item mapper si in
>          let sli =
>            List.map
>              (fun (n, v) ->
>                [%stri let [%p pvar n] = [%e str v]])
>              !defs in
>          defs := [];
>          (si::sli) @ acc) [] li in
>      List.rev li
> ...
>
> The question is how to pass the location information for [%stri]
> generated code (loc in my example)? Of course I can write
>
> {[%stri let [%p pvar n] = [%e str v]] with pstr_loc = loc}
>
> but I would like the location of all nested expressions to be set to
> loc as well.
>
> - Dmitry Bely
>