Merge branch 'AssignmentCollection.__bool__' into 'master'

AssignmentCollection.__bool__

See merge request pycodegen/pystencils!108

pystencils/gpucuda/kernelcreation.py

@@ -16,6 +16,7 @@ def create_cuda_kernel(assignments,
                        ghost_layers=None,
                        skip_independence_check=False,
                        use_textures_for_interpolation=True):
+    assert assignments, "Assignments must not be empty!"
     fields_read, fields_written, assignments = add_types(assignments, type_info, not skip_independence_check)
     all_fields = fields_read.union(fields_written)
     read_only_fields = set([f.name for f in fields_read - fields_written])

pystencils/kernelcreation.py

-from types import MappingProxyType
 from itertools import combinations
+from types import MappingProxyType
 
 import sympy as sp
 
@@ -74,6 +74,7 @@ def create_kernel(assignments,
                [0., 0., 0., 0., 0.]])
     """
     # ----  Normalizing parameters
+    assert assignments, "Assignments must not be empty!"
     split_groups = ()
     if isinstance(assignments, AssignmentCollection):
         if 'split_groups' in assignments.simplification_hints:

pystencils/simp/assignment_collection.py

@@ -404,6 +404,9 @@ class AssignmentCollection:
     def __eq__(self, other):
         return set(self.all_assignments) == set(other.all_assignments)
 
+    def __bool__(self):
+        return bool(self.all_assignments)
+
 
 class SymbolGen:
     """Default symbol generator producing number symbols ζ_0, ζ_1, ..."""