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-rw-r--r--gnu/packages.scm26
1 files changed, 25 insertions, 1 deletions
diff --git a/gnu/packages.scm b/gnu/packages.scm
index 14ad75561c..26d87c6b16 100644
--- a/gnu/packages.scm
+++ b/gnu/packages.scm
@@ -28,6 +28,7 @@
#:use-module (ice-9 vlist)
#:use-module (ice-9 match)
#:use-module (srfi srfi-1)
+ #:use-module (srfi srfi-11)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-39)
#:export (search-patch
@@ -45,7 +46,9 @@
package-transitive-dependents
package-covering-dependents
- check-package-freshness))
+ check-package-freshness
+
+ specification->package))
;;; Commentary:
;;;
@@ -326,3 +329,24 @@ but ~a is available upstream~%")
(case key
((getaddrinfo-error ftp-error) #f)
(else (apply throw key args))))))
+
+(define (specification->package spec)
+ "Return a package matching SPEC. SPEC may be a package name, or a package
+name followed by a hyphen and a version number. If the version number is not
+present, return the preferred newest version."
+ (let-values (((name version)
+ (package-name->name+version spec)))
+ (match (find-best-packages-by-name name version)
+ ((p) ; one match
+ p)
+ ((p x ...) ; several matches
+ (warning (_ "ambiguous package specification `~a'~%") spec)
+ (warning (_ "choosing ~a from ~a~%")
+ (package-full-name p)
+ (location->string (package-location p)))
+ p)
+ (_ ; no matches
+ (if version
+ (leave (_ "~A: package not found for version ~a~%")
+ name version)
+ (leave (_ "~A: unknown package~%") name))))))