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01/02: utils: Add 'false-if-file-not-found'.
From: |
Ludovic Courtès |
Subject: |
01/02: utils: Add 'false-if-file-not-found'. |
Date: |
Wed, 14 Mar 2018 07:17:33 -0400 (EDT) |
civodul pushed a commit to branch core-updates
in repository guix.
commit 5c6391b33acaaae75746f6ae30089d4aec14c349
Author: Ludovic Courtès <address@hidden>
Date: Sun Mar 11 22:04:12 2018 +0100
utils: Add 'false-if-file-not-found'.
* guix/build/utils.scm (false-if-file-not-found): New macro.
---
guix/build/utils.scm | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/guix/build/utils.scm b/guix/build/utils.scm
index d7ed3d5..ab309aa 100644
--- a/guix/build/utils.scm
+++ b/guix/build/utils.scm
@@ -1,5 +1,5 @@
;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès
<address@hidden>
+;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès
<address@hidden>
;;; Copyright © 2013 Andreas Enge <address@hidden>
;;; Copyright © 2013 Nikita Karetnikov <address@hidden>
;;; Copyright © 2015 Mark H Weaver <address@hidden>
@@ -61,6 +61,7 @@
delete-file-recursively
file-name-predicate
find-files
+ false-if-file-not-found
search-path-as-list
set-path-environment-variable
@@ -396,6 +397,15 @@ also be included. If FAIL-ON-ERROR? is true, raise an
exception upon error."
stat)
string<?)))
+(define-syntax-rule (false-if-file-not-found exp)
+ "Evaluate EXP but return #f if it raises to 'system-error with ENOENT."
+ (catch 'system-error
+ (lambda () exp)
+ (lambda args
+ (if (= ENOENT (system-error-errno args))
+ #f
+ (apply throw args)))))
+
;;;
;;; Search paths.