> On Jul 4, 2017, at 1:39 PM, reilithion <reilith...@gmail.com> wrote:
>
> I'd like to be able to get source location information from behind two or
> more layers of macros.
>
> Unfortunately, the srcloc that gets stored ends up being the location of the
> simplifying macro. Not what I want. I need to somehow forward the srcloc of
> its use-location.
You can stash the original caller `stx` as a syntax property, which is a
convenient way of passing "secret" arguments between macros:
#lang racket
(require "a.rkt" "b.rkt")
(getloc (simple-data unlucky 262))
#lang racket
(provide simple-data)
(require "a.rkt")
(define-syntax (simple-data stx)
(syntax-case stx ()
[(_ name x)
(syntax-property #'(mk-data 'name x 42) 'caller-stx stx)]))
#lang racket
(provide mk-data getloc)
(struct data-internal
(name x y srcloc)
#:guard (λ (n x y srcloc struct-name)
(unless (real? x)
(raise-argument-error 'data-internal "real?" x))
(unless (real? y)
(raise-argument-error 'data-internal "real?" y))
(values n x y srcloc)))
(define-syntax (mk-data stx)
(syntax-case stx ()
[(_ name x y)
(let ([stx (or (syntax-property stx 'caller-stx) stx)])
#`(data-internal name x y (srcloc #,(syntax-source stx)
#,(syntax-line stx)
#,(syntax-column stx)
#,(syntax-position stx)
#,(syntax-span stx))))]))
(define (getloc d) (srcloc->string (data-internal-srcloc d)))
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