X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/4ee476bc29b80fca2faabb4bd286ca70c98f7a44..f458e64e36509fa8c204f1dbcafff1d3dc059619:/src/pset-impl.lisp

diff --git a/src/pset-impl.lisp b/src/pset-impl.lisp
index 60674ff..e6986a5 100644
--- a/src/pset-impl.lisp
+++ b/src/pset-impl.lisp
@@ -74,6 +74,14 @@
 		 (error "Symbol `~A' not external in package `~A'"
 			name (package-name package)))))))))
 
+(let ((truish '("true" "t" "yes" "verily"))
+      (falsish '("false" "nil" "no" "nowise")))
+  (defun truishp (string)
+    "Convert STRING to a boolean."
+    (cond ((member string truish :test #'string=) t)
+	  ((member string falsish :test #'string=) nil)
+	  (t (error "Unrecognized boolean value `~A'" string)))))
+
 ;;;--------------------------------------------------------------------------
 ;;; Property representation.
 
@@ -114,6 +122,20 @@
     ((value symbol) (type (eql :symbol)) (wanted (eql :id)))
   (frob-identifier (symbol-name value)))
 
+;;; Boolean.
+
+(defmethod coerce-property-value
+    ((value symbol) (type (eql :symbol)) (wanted (eql :boolean)))
+  value)
+
+(defmethod coerce-property-value
+    ((value string) (type (eql :id)) (wanted (eql :boolean)))
+  (truishp value))
+
+(defmethod coerce-property-value
+    ((value integer) (type (eql :int)) (wanted (eql :boolean)))
+  (not (zerop value)))
+
 ;;; Types.
 
 (defmethod coerce-property-value