From: Matt Birkholz <matt@birchwood-abbey.net>
Date: Mon, 12 Mar 2018 16:12:48 +0000 (-0700)
Subject: glib: Add guarantee-color.
X-Git-Tag: mit-scheme-pucked-x11-0.2.2~50
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=7c7a78898a662a7d9936eaf1cd36289576cbe2e3;p=mit-scheme.git

glib: Add guarantee-color.
---

diff --git a/src/glib/glib.scm b/src/glib/glib.scm
index 252fa0580..1fbdd0b9f 100644
--- a/src/glib/glib.scm
+++ b/src/glib/glib.scm
@@ -114,6 +114,11 @@ Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
     (set-color-blue! color blue)
     (set-color-alpha! color alpha)
     color))
+
+(define (guarantee-color object operator)
+  (if (color? object)
+      object
+      (error:wrong-type-argument object "a color" operator)))
 
 ;;; GLib Mutex