3 files changed, 49 insertions, 1 deletions
diff --git a/gnuradio-core/src/lib/general/gr_feval.cc b/gnuradio-core/src/lib/general/gr_feval.cc
index 532a14018..3617620b5 100644
--- a/gnuradio-core/src/lib/general/gr_feval.cc
+++ b/gnuradio-core/src/lib/general/gr_feval.cc
@@ -50,6 +50,14 @@ gr_feval_ll::eval(long x)
   return 0;
 }
 
+gr_feval::~gr_feval(){}
+
+void
+gr_feval::eval(void)
+{
+  // nop
+}
+
 /*
  * Trivial examples showing C++ (transparently) calling Python
  */
@@ -70,3 +78,9 @@ gr_feval_ll_example(gr_feval_ll *f, long x)
 {
   return f->eval(x);
 }
+
+void
+gr_feval_example(gr_feval *f)
+{
+  f->eval();
+}
diff --git a/gnuradio-core/src/lib/general/gr_feval.h b/gnuradio-core/src/lib/general/gr_feval.h
index 18bb4007e..a2f7020a4 100644
--- a/gnuradio-core/src/lib/general/gr_feval.h
+++ b/gnuradio-core/src/lib/general/gr_feval.h
@@ -85,11 +85,31 @@ public:
 };
 
 /*!
+ * \brief base class for evaluating a function: void -> void
+ *
+ * This class is designed to be subclassed in Python or C++
+ * and is callable from both places.  It uses SWIG's
+ * "director" feature to implement the magic.
+ * It's slow. Don't use it in a performance critical path.
+ */
+class gr_feval
+{
+public:
+  gr_feval() {}
+  virtual ~gr_feval();
+
+  /*!
+   * \brief override this to define the function
+   */
+  virtual void eval();
+};
+
+/*!
  * \brief trivial examples / test cases showing C++ calling Python code
  */
 double     gr_feval_dd_example(gr_feval_dd *f, double x);
 gr_complex gr_feval_cc_example(gr_feval_cc *f, gr_complex x);
 long       gr_feval_ll_example(gr_feval_ll *f, long x);
-
+void       gr_feval_example(gr_feval *f);
 
 #endif /* INCLUDED_GR_FEVAL_H */
diff --git a/gnuradio-core/src/lib/general/gr_feval.i b/gnuradio-core/src/lib/general/gr_feval.i
index 586e143d0..09d98b648 100644
--- a/gnuradio-core/src/lib/general/gr_feval.i
+++ b/gnuradio-core/src/lib/general/gr_feval.i
@@ -24,6 +24,7 @@
 %feature("director") gr_feval_dd;
 %feature("director") gr_feval_cc;
 %feature("director") gr_feval_ll;
+%feature("director") gr_feval;
 
 
 %rename(feval_dd) gr_feval_dd;
@@ -56,6 +57,16 @@ public:
   virtual long eval(long x);
 };
 
+%rename(feval) gr_feval;
+class gr_feval
+{
+public:
+  gr_feval() {}
+  virtual ~gr_feval();
+
+  virtual void eval();
+};
+
 
 // examples / test cases
 
@@ -67,3 +78,6 @@ gr_complex gr_feval_cc_example(gr_feval_cc *f, gr_complex x);
 
 %rename(feval_ll_example) gr_feval_ll_example;
 long gr_feval_ll_example(gr_feval_ll *f, long x);
+
+%rename(feval_example) gr_feval_example;
+void gr_feval_example(gr_feval *f);