Minor module interface cleanups

1 files changed, 7 insertions, 0 deletions

diff --git a/build2/variable b/build2/variable
index a5f2ea5..c506a3e 100644
--- a/build2/variable
+++ b/build2/variable
@@ -252,6 +252,13 @@ namespace build2
   template <typename T> const T* cast_null (const value&);
   template <typename T> const T* cast_null (const lookup&);
 
+  // As above but returns false if the value is NULL (or not defined, in case
+  // of lookup). Note that the template argument is only for documentation and
+  // should be bool (or semantically compatible).
+  //
+  template <typename T> T cast_false (const value& v);
+  template <typename T> T cast_false (const lookup& l);
+
   // Assign value type to the value. In the second version the variable is
   // optional and is only used for diagnostics.
   //