From 1c0e1237137e74bef96bfd7f8ea0ced887197c14 Mon Sep 17 00:00:00 2001
From: Ingmar Schoegl <ischoegl@lsu.edu>
Date: Thu, 23 Jan 2020 13:56:44 -0600
Subject: [PATCH] [numerics] Use Const1 objects in Python

- replace Python lambda function defining constant Func1 variants by
  pre-existing Const1 class defined in C++
---
 interfaces/cython/cantera/_cantera.pxd |  9 +++++++--
 interfaces/cython/cantera/func1.pyx    | 17 ++++++++++-------
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/interfaces/cython/cantera/_cantera.pxd b/interfaces/cython/cantera/_cantera.pxd
index 2b4ebebbbee..542ebc334f4 100644
--- a/interfaces/cython/cantera/_cantera.pxd
+++ b/interfaces/cython/cantera/_cantera.pxd
@@ -43,6 +43,10 @@ cdef extern from "cantera/numerics/Func1.h":
         CxxTabulated1(vector[double]&, vector[double]&) except +translate_exception
         double eval(double) except +translate_exception
 
+    cdef cppclass CxxConst1 "Cantera::Const1":
+        CxxConst1(double) except +translate_exception
+        double eval(double) except +translate_exception
+
 cdef extern from "cantera/base/xml.h" namespace "Cantera":
     cdef cppclass XML_Node:
         XML_Node* findByName(string)
@@ -1015,8 +1019,9 @@ cdef class Func1:
     cdef CxxFunc1* func
     cdef object callable
     cdef object exception
-    cpdef void __set_callback(self, object) except *
-    cpdef void __set_tables(self, object, object) except *
+    cpdef void _set_callback(self, object) except *
+    cpdef void _set_const(self, double) except *
+    cpdef void _set_tables(self, object, object) except *
 
 cdef class ReactorBase:
     cdef CxxReactorBase* rbase
diff --git a/interfaces/cython/cantera/func1.pyx b/interfaces/cython/cantera/func1.pyx
index f70a3354a8f..a8f5e1ce15d 100644
--- a/interfaces/cython/cantera/func1.pyx
+++ b/interfaces/cython/cantera/func1.pyx
@@ -87,24 +87,24 @@ cdef class Func1:
             c = args[0]
             if hasattr(c, '__call__'):
                 # callback function
-                self.__set_callback(c)
+                self._set_callback(c)
             else:
                 arr = np.array(c)
                 try:
                     if arr.ndim == 0:
                         # handle constants or unsized numpy arrays
                         k = float(c)
-                        self.__set_callback(lambda t: k)
+                        self._set_const(k)
                     elif arr.size == 1:
                         # handle lists, tuples or numpy arrays with a single element
                         k = float(c[0])
-                        self.__set_callback(lambda t: k)
+                        self._set_const(k)
                     elif arr.ndim == 2:
                         # tabulated function (single argument)
                         if arr.shape[1] == 2:
                             time = arr[:, 0]
                             fval = arr[:, 1]
-                            self.__set_tables(time, fval)
+                            self._set_tables(time, fval)
                         else:
                             raise ValueError(
                                 "Invalid dimensions: specification of "
@@ -121,17 +121,20 @@ cdef class Func1:
         elif len(args) == 2:
             # tabulated function (two arguments mimic C++ interface)
             time, fval = args
-            self.__set_tables(time, fval)
+            self._set_tables(time, fval)
 
         else:
             raise ValueError("Invalid number of arguments")
 
 
-    cpdef void __set_callback(self, c) except *:
+    cpdef void _set_callback(self, c) except *:
         self.callable = c
         self.func = new CxxFunc1(func_callback, <void*>self)
 
-    cpdef void __set_tables(self, time, fval) except *:
+    cpdef void _set_const(self, double c) except *:
+        self.func = <CxxFunc1*>(new CxxConst1(c))
+
+    cpdef void _set_tables(self, time, fval) except *:
         cdef vector[double] tvec, fvec
         for t in time:
             tvec.push_back(t)