New variables architecture

Now operator[] is only used for lookup.

1 files changed, 7 insertions, 0 deletions

diff --git a/build/variable.ixx b/build/variable.ixx
index c0059c5..2cbe519 100644
--- a/build/variable.ixx
+++ b/build/variable.ixx
@@ -53,4 +53,11 @@ namespace build
     p->reset (new list_value (std::move (v)));
     return *this;
   }
+
+  inline const value_proxy& value_proxy::
+  operator= (nullptr_t) const
+  {
+    p->reset ();
+    return *this;
+  }
 }