python wrapper for custom binary diffusion fcn

photochem/cython/PhotochemVars.pyx

@@ -99,6 +99,26 @@ cdef class PhotochemVars:
       cdef ndarray arr = np.empty(dim1, np.double)
       var_pxd.photochemvars_edd_get(&self._ptr, &dim1, <double *>arr.data)
       return arr
+
+  property custom_binary_diffusion_fcn:
+    "A function for specifying a custom binary diffusion parameter (b_ij)"
+    def __set__(self, object fcn):
+      cdef uintptr_t fcn_l
+      cdef var_pxd.binary_diffusion_fcn fcn_c
+      if fcn is None:
+        fcn_l = 0
+        fcn_c = NULL
+      else:
+        argtypes = (ct.c_double, ct.c_double, ct.c_double)
+        restype = ct.c_double
+        if not fcn.ctypes.argtypes == argtypes:
+          raise PhotoException("The callback function has the wrong argument types.")
+        if not fcn.ctypes.restype == restype:
+          raise PhotoException("The callback function has the wrong return type.")
+        fcn_l = fcn.address
+        fcn_c = <var_pxd.binary_diffusion_fcn> fcn_l
+
+      var_pxd.photochemvars_custom_binary_diffusion_fcn_set(&self._ptr, fcn_c)
 
   property photon_flux:
     "ndarray[double,dim=1], shape (nw). photon/cm^2/s in each wavelength bin hitting planet."

photochem/cython/PhotochemVars_pxd.pxd

@@ -4,6 +4,7 @@ cdef extern from "<stdbool.h>":
 
 # callback signatures
 ctypedef void (*time_dependent_flux_fcn)(double tn, int nw, double *photon_flux)
+ctypedef double (*binary_diffusion_fcn)(double mu_i, double mubar, double T)
 
 cdef extern void allocate_photochemvars(void *ptr)
 cdef extern void deallocate_photochemvars(void *ptr)
@@ -27,6 +28,8 @@ cdef extern void photochemvars_temperature_get(void *ptr, int *dim1, double *tem
 cdef extern void photochemvars_edd_get_size(void *ptr, int *dim1)
 cdef extern void photochemvars_edd_get(void *ptr, int *dim1, double *arr)
 
+cdef extern void photochemvars_custom_binary_diffusion_fcn_set(void *ptr, binary_diffusion_fcn fcn)
+
 cdef extern void photochemvars_photon_flux_get_size(void *ptr, int *dim1)
 cdef extern void photochemvars_photon_flux_get(void *ptr, int *dim1, double *arr)
 

photochem/fortran/PhotochemVars_wrapper.f90

@@ -118,6 +118,20 @@ subroutine photochemvars_edd_get(ptr, dim1, arr) bind(c)
     call c_f_pointer(ptr, var)
     arr = var%edd
   end subroutine
+
+  subroutine photochemvars_custom_binary_diffusion_fcn_set(ptr, fcn_c) bind(c)
+    use photochem_types, only: binary_diffusion_fcn
+    type(c_ptr), intent(in) :: ptr
+    type(c_funptr), value, intent(in) :: fcn_c
+
+    procedure(binary_diffusion_fcn), pointer :: fcn_f
+    type(PhotochemVars), pointer :: var
+
+    call c_f_pointer(ptr, var)
+    call c_f_procpointer(fcn_c, fcn_f)
+    var%custom_binary_diffusion_fcn => fcn_f
+
+  end subroutine
 
   subroutine photochemvars_photon_flux_get_size(ptr, dim1) bind(c)
     type(c_ptr), intent(in) :: ptr