[REF] changes suggested by @guewen

Set a keyword argument on the context to better respect the convention.
Make it clear in docstrings that the side-effects on field_names are
intended.
Allow the context to contain iterable types supported by the ORM.

stock_available/product.py

@@ -56,8 +56,10 @@ class ProductProduct(orm.Model):
         The sub-modules MUST call super()._product_available BEFORE their own
                 computations
 
-        Side-effect warning: This method may change the list passed as the
-            field_names parameter, which will then alter the caller's state."""
+        Side-effect warning: By design, we want to change the behavior of the
+            caller (make it aware that an extra field is being computed).
+            For this, this method MAY change the list passed as the parameter
+            `field_names`."""
         # If we didn't get a field_names list, there's nothing to do
         if field_names is None:
             return super(ProductProduct, self)._product_available(

stock_available_immediately/product.py

@@ -26,15 +26,17 @@ class product_immediately_usable(orm.Model):
     """Subtract incoming qty from immediately_usable_qty
 
     We don't need to override the function fields, the module stock_available
-    takes of it for us.
-
-    Side-effect warning: This method may change the list passed as the
-        field_names parameter, which will then alter the caller's state."""
+    takes care of it for us."""
     _inherit = 'product.product'
 
     def _product_available(self, cr, uid, ids, field_names=None,
                            arg=False, context=None):
-        """Ignore the incoming goods in the quantity available to promise"""
+        """Ignore the incoming goods in the quantity available to promise
+
+        Side-effect warning: By design, we want to change the behavior of the
+            caller (make it aware that an extra field is being computed).
+            For this, this method MAY change the list passed as the parameter
+            `field_names`."""
         # If we didn't get a field_names list, there's nothing to do
         if field_names is None or 'immediately_usable_qty' not in field_names:
             return super(product_immediately_usable, self)._product_available(

stock_available_mrp/product.py

@@ -73,10 +73,12 @@ class product_product(orm.Model):
         return res
 
     def _compute_potential_qty_from_bom(self, cr, uid, bom_id, to_uom,
-                                        context):
+                                        context=None):
         """Compute the potential qty from BoMs with components available"""
         bom_obj = self.pool['mrp.bom']
         uom_obj = self.pool['product.uom']
+        if context is None:
+            context = {}
         if 'uom' in context:
             context_wo_uom = context.copy()
             del context_wo_uom['uom']

stock_available_sale/product.py

@@ -134,7 +134,7 @@ class ProductProduct(orm.Model):
         # location
         if context.get('location', False):
             # Either a single or multiple locations can be in the context
-            if not isinstance(context['location'], list):
+            if isinstance(context['location'], (int, long)):
                 location_ids = [context['location']]
             else:
                 location_ids = context['location']