Implement add() to add cnfvars to cnfvar lists directly from tuples

The CnfList class already has some functionality for initialization
directly from tuples and the Cnf class already has some functionality
like add_child() for adding a cnfvar from a tuple to Cnf instance's
CnfList instance children. To complete the syntactic sugar circle,
also provide the further possibility to add a CnfList item straight
from a tuple using add() instead of the more raw and manual append()
which can also handle both Cnf instances and tuples similarly to the
previous two options above.

diff --git a/src/cnfvar/model.py b/src/cnfvar/model.py
index aff7c38..a8beb5c 100644 (file)
--- a/src/cnfvar/model.py
+++ b/src/cnfvar/model.py
@@ -238,6 +238,27 @@ class BaseCnfList(list):
     def __add__(self, other):
         return CnfList(super().__add__(other))
 
+    def add(self, *args, **kwargs):
+        """
+        Add a CNF variable to the list.
+
+        Arguments can either be a single instance of the :py:class:`Cnf`
+        class or a list of arguments to be passed to the constructor of
+        that class. Similar to the :py:func:`add_child` method for a `Cnf`.
+
+        :returns: the instance that was created
+        :rtype: :py:class:`Cnf`
+        """
+        # support passing a Cnf instance
+        if len(args) == 1 and not kwargs:
+            cnf = args[0]
+            assert isinstance(cnf, Cnf), "A Cnf instance is mandatory with one argument"
+        else:
+            cnf = Cnf(*args, **kwargs)
+
+        self.append(cnf)
+        return cnf
+
 
 class BaseCnf:
     """Base class representing a CNF variable with minimal functionality."""
@@ -335,8 +356,7 @@ class BaseCnf:
         # support passing a Cnf instance
         if len(args) == 1 and not kwargs:
             cnf = args[0]
-            assert isinstance(cnf, Cnf), \
-                   "With one argument, a Cnf instance is mandatory"
+            assert isinstance(cnf, Cnf), "A Cnf instance is mandatory with one argument"
         else:
             cnf = Cnf(*args, **kwargs)