Changeset 1942

Timestamp:

08/28/10 20:05:56 (2 years ago)

Author:

dsimcha

Message:

std.traits: Add isAssignable.

Files:

• trunk/docsrc/changelog.dd (modified) (1 diff)
• trunk/phobos/std/traits.d (modified) (1 diff)

trunk/docsrc/changelog.dd

@@ -7 +7 @@
-
-    $(WHATSNEW
-
-
+
-    $(LI std.process: Added environment, an AA-like interface for environment variables.)
-    $(LI std.range:  Iota, Stride, Transversal, FrontTransveral now support slicing where possible.)
-    $(LI std.range:  Added Lockstep, hasLvalueElements.)
-    $(LI std.range:  Added virtual function-based wrappers (InputRangeObject, OutputRangeObject) for when a binary interface to a range is required.)
-
+
+
-    $(LI std.typetuple:  Added anySatisfy.)
-    $(LI $(LINK2 phobos/std_stopwatch.html,std.swopwatch):  Added StopWatch, Ticks, systime, apptime, comparingBenchmark, measureTime.)

trunk/phobos/std/traits.d

@@ -1884 +1884 @@
-}
-
+/**
+Returns $(D true) iff a value of type $(D Rhs) can be assigned to a variable of
+type $(D Lhs).
+
+Examples:
+---
+static assert(isAssignable!(long, int));
+static assert(!isAssignable!(int, long));
+static assert(isAssignable!(const(char)[], string));
+static assert(!isAssignable!(string, char[]));
+---
+*/
+template isAssignable(Lhs, Rhs) {
+    enum bool isAssignable = is(typeof({
+        Lhs l;
+        Rhs r;
+        l = r;
+        return l;
+    }));
+}
+
+unittest {
+    static assert(isAssignable!(long, int));
+    static assert(!isAssignable!(int, long));
+    static assert(isAssignable!(const(char)[], string));
+    static assert(!isAssignable!(string, char[]));
+}
+
-
-/*