Cantera/Extending C API

This article discusses extending Cantera's C API. This allows you to create a new class or function in Cantera, and create a handle for that object or function from Cantera's Python API.

To illustrate this procedure, I'll be adding a method to Cantera's ReactorBase class to remove all of the walls in a reactor. This article covers the following steps:

• Adding a C++ function to the ReactorBase object
• Extending Cantera's C API to include the new function
• Extending Cantera's Python-C interface to utilize the new function
• Calling the method from Python

Add New C++ Method

I'll add the following two methods to ReactorBase.cpp:

===================================================================
--- ReactorBase.cpp	(revision 2)
+++ ReactorBase.cpp	(working copy)
@@ -72,6 +72,30 @@
     m_nwalls++;
 }

+void ReactorBase::removeWall(Wall& w)
+{
+    vector_int::iterator iL = m_lr.begin();
+    for( std::vector<Wall*>::iterator iW = m_wall.begin();
+            iW != m_wall.end();
+            ++iW, ++iL ) {
+        if ( (*iW) == &w) {
+            m_wall.erase( iW );
+            m_lr.erase( iL );
+        }
+    }
+}
+
+void ReactorBase::removeWalls()
+{
+    vector_int::iterator iL = m_lr.begin();
+    for( std::vector<Wall*>::iterator iW = m_wall.begin();
+            iW != m_wall.end();
+            ++iW, ++iL ) {
+        m_wall.erase(iW);
+        m_lr.erase(iL);
+    }
+}
+
 Wall& ReactorBase::wall(size_t n)
 {
     return *m_wall[n];

and modify the header file as follows:

===================================================================
--- include/cantera/zeroD/ReactorBase.h	(revision 2)
+++ include/cantera/zeroD/ReactorBase.h	(working copy)
@@ -91,6 +91,11 @@
     }

     void addWall(Wall& w, int lr);
+
+    void removeWall(Wall& w);
+
+    void removeWalls();
+
     Wall& wall(size_t n);