Apply first cut of handles method generator. Patch courtesy of maard++.

build/Makefile.in

@@ -171,6 +171,7 @@ CORE_SOURCES = \
   src/core/traits.pm \
   src/core/metaops.pm \
   src/core/operators.pm \
+  src/glue/handles.pm \
   src/glue/subset.pm \
   src/cheats/trait-export.pm \
   src/cheats/num.pm \

src/glue/handles.pm

@@ -0,0 +1,20 @@
+our sub add_handles_method_helper($metaclass, $attr, $meth-name, $meth-rename = $meth-name) {
+    $metaclass.add_method($metaclass, $meth-name, (method (|$c) {
+        pir::getattribute__PPS(self, $attr)."$meth-rename"(|$c); 
+    }).clone() ); 
+}
+
+our sub add_handles_method($metaclass, $attr_name, $expr) {
+    for ($expr) -> $x {
+        given $x {
+           when Str { add_handles_method_helper($metaclass, $attr_name, $x); }
+           when Parcel { 
+               for $x.list -> $x { add_handles_method_helper($metaclass, $attr_name, $x); }
+           }
+           when Pair { 
+               add_handles_method_helper($metaclass, $attr_name, $x.key, $x.value);
+           }
+           default { die sprintf("add_handles_method can't handle %s in list", $x.WHAT); }
+        }
+    }
+}