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[core-utils] use custom unbound-variable exception printer

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When a guile coder uses a variable but omits use-modules, this code
will scan *all* available modules and offer the appropriate module
name.

Before:
Unbound variable: gnc-build-url

After:
Unbound variable: gnc-build-url. Did you forget (use-module (sw_gnc_html))?
This commit is contained in:
Christopher Lam 2020-12-13 20:36:02 +08:00
parent c2ba88d91d
commit 6f9517845a
1 changed files with 34 additions and 0 deletions
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34
bindings/guile/core-utils.scm
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@ -29,6 +29,8 @@
(eval-when (compile load eval expand)
(load-extension "libgnucash-guile" "gnc_guile_bindings_init"))
(use-modules (srfi srfi-26))
(use-modules (ice-9 match))
(use-modules (ice-9 i18n))
(export N_)
@ -73,3 +75,35 @@
(define gnc:string-locale<? string-locale<?)
(define gnc:string-locale>? string-locale>?)
;; Custom unbound-variable exception printer: instead of generic "In
;; procedure module-lookup: Unbound variable: varname", it will first
;; search all available modules to identify missing (use-modules) in
;; header, and offer hint to add it. This is adapted from Guix source.
(define (known-variable-definition variable)
(define seen (make-hash-table))
(let lp ((modules (list (resolve-module '() #f #f #:ensure #f))) (retval '()))
(match modules
(() retval)
(((? (cut hash-ref seen <>)) . tail) (lp tail retval))
((head tail ...)
(hash-set! seen head #t)
(let ((next (append tail (hash-map->list (lambda (name module) module)
(module-submodules head)))))
(match (and=> (module-public-interface head)
(cut module-local-variable <> variable))
(#f (lp next retval))
(_ (lp next (cons (module-name head) retval)))))))))
(define (print-unbound-variable-error port key args default-printer)
(match args
((proc message (variable) _ ...)
(format port "Unbound variable: ~a. " variable)
(match (known-variable-definition variable)
(() (format port "It is a typo, or inaccessible in current module."))
((mod) (format port "Did you forget (use-module ~s)?" mod))
(modules (format port "It is defined in one of the following modules\n")
(for-each (cut format port "(use-module ~s)\n" <>) modules))))
(_ (default-printer))))
(set-exception-printer! 'unbound-variable print-unbound-variable-error)