6 files changed, 20 insertions, 12 deletions
diff --git a/PMC b/PMC
-Subproject 9370c57fb44b5388757dcf8ae1ffa6c0885b1e6
+Subproject ba5d60f84cd333965050c6db3e9bf4850d22041
diff --git a/include/gras/element.i b/include/gras/element.i
index ed21367..8dc360b 100644
--- a/include/gras/element.i
+++ b/include/gras/element.i
@@ -17,7 +17,7 @@
 ////////////////////////////////////////////////////////////////////////
 %include <std_string.i>
 %include <gras/gras.hpp>
-%include <gras/io_signature.i>
+%import <gras/io_signature.i>
 %include <gras/element.hpp>
 
 ////////////////////////////////////////////////////////////////////////
diff --git a/include/gras/io_signature.hpp b/include/gras/io_signature.hpp
index a637c2c..002f79a 100644
--- a/include/gras/io_signature.hpp
+++ b/include/gras/io_signature.hpp
@@ -5,7 +5,6 @@
 
 #include <vector>
 #include <stdexcept>
-#include <cstdlib>
 
 namespace gras
 {
@@ -16,7 +15,7 @@ namespace gras
  * Properties are a maximum and minimum number of ports,
  * and an item size in bytes for each port.
  */
-struct IOSignature : std::vector<size_t>
+struct IOSignature : std::vector<unsigned>
 {
     static const int IO_INFINITE = ~0;
 
@@ -28,7 +27,7 @@ struct IOSignature : std::vector<size_t>
     }
 
     //! Create a signature with a single item size
-    IOSignature(const size_t size)
+    IOSignature(const unsigned size)
     {
         this->push_back(size);
         this->set_min_streams(IO_INFINITE);
@@ -47,7 +46,7 @@ struct IOSignature : std::vector<size_t>
     }
 
     //! Create a signature from a vector of IO widths
-    IOSignature(const std::vector<size_t> &sig)
+    IOSignature(const std::vector<unsigned> &sig)
     {
         this->assign(sig.begin(), sig.end());
         this->set_min_streams(IO_INFINITE);
@@ -72,7 +71,7 @@ struct IOSignature : std::vector<size_t>
         return this;
     };
 
-    const size_t &at(const size_t index) const
+    const unsigned &at(const unsigned index) const
     {
         if (this->empty())
         {
@@ -80,12 +79,12 @@ struct IOSignature : std::vector<size_t>
         }
         if (this->size() > index)
         {
-            return std::vector<size_t>::at(index);
+            return std::vector<unsigned>::at(index);
         }
         return this->back();
     }
 
-    const size_t &operator[](const size_t index) const
+    const unsigned &operator[](const unsigned index) const
     {
         return this->at(index);
     }
@@ -110,12 +109,12 @@ struct IOSignature : std::vector<size_t>
         return _max_streams;
     }
 
-    int sizeof_stream_item(const size_t index) const
+    int sizeof_stream_item(const unsigned index) const
     {
         return this->at(index);
     }
 
-    const std::vector<size_t> &sizeof_stream_items(void) const
+    const std::vector<unsigned> &sizeof_stream_items(void) const
     {
         return *this;
     }
diff --git a/include/gras/io_signature.i b/include/gras/io_signature.i
index b67a5ed..be9a3fd 100644
--- a/include/gras/io_signature.i
+++ b/include/gras/io_signature.i
@@ -12,13 +12,13 @@
 %ignore gras::IOSignature::operator[]; //ignore warnings about %extend
 
 %include <std_vector.i>
-%template (std_vector_gras_io_signature_size_t) std::vector<size_t>;
+%template (std_vector_gras_io_signature_unsigned) std::vector<unsigned>;
 
 %include <gras/io_signature.hpp>
 
 %extend gras::IOSignature
 {
-    const size_t &__getitem__(const size_t index)
+    const unsigned &__getitem__(const unsigned index)
     {
         return ($self)->at(index);
     }
diff --git a/python/gras/GRAS_Block.i b/python/gras/GRAS_Block.i
index cf23b2a..0becfd0 100644
--- a/python/gras/GRAS_Block.i
+++ b/python/gras/GRAS_Block.i
@@ -78,6 +78,7 @@ struct PyGILPhondler
 #include <iostream>
 %}
 
+%include <gras/io_signature.i>
 %include <gras/block.i>
 
 ////////////////////////////////////////////////////////////////////////
diff --git a/tests/io_sig_test.py b/tests/io_sig_test.py
index 876e53f..3cd90bf 100644
--- a/tests/io_sig_test.py
+++ b/tests/io_sig_test.py
@@ -9,5 +9,13 @@ class IOSigTest(unittest.TestCase):
         io = gras.IOSignature()
         self.assertEqual(len(io), 0)
 
+    def test_io_sig_extend(self):
+        io = gras.IOSignature([5, 6, 7])
+        self.assertEqual(len(io), 3)
+        self.assertEqual(io[0], 5)
+        self.assertEqual(io[1], 6)
+        self.assertEqual(io[2], 7)
+        self.assertEqual(io[3], 7) #auto extend
+
 if __name__ == '__main__':
     unittest.main()