ENH: add set_dynamics() method for backward compatibility (#400)

src/ampform/helicity/__init__.py

@@ -11,6 +11,7 @@
 import logging
 import operator
 import sys
+import warnings
 from collections import OrderedDict, abc
 from functools import reduce
 from typing import (
@@ -377,6 +378,22 @@ def naming(self) -> NameGenerator:
     def reaction(self) -> ReactionInfo:
         return self.__reaction
 
+    def set_dynamics(
+        self, particle_name: str, dynamics_builder: ResonanceDynamicsBuilder
+    ) -> None:
+        """Assign a `.ResonanceDynamicsBuilder` for a specific resonance.
+
+        .. deprecated:: 0.16.0
+            Use the `~.DynamicsSelector.assign()` method of the `.dynamics` attribute
+            instead.
+        """
+        warnings.warn(
+            "set_dynamics() will be removed in favor of dynamics.assign()",
+            category=DeprecationWarning,
+            stacklevel=1,
+        )
+        self.dynamics.assign(particle_name, dynamics_builder)
+
     def formulate(self) -> HelicityModel:
         self.__ingredients.reset()
         main_intensity = self.__formulate_top_expression()