Add Traits.traithandler back reference so custom Traits can find and read values of other traits on the handler. See #2801

CHANGELOG.md

@@ -6,6 +6,8 @@
   bugs etc in-game (InspectorCaracal)
 - [Feat][pull3586]: Add ANSI color support `|U`, `|I`, `|i`, `|s`, `|S` for
 underline reset, italic/reset and strikethrough/reset (0xDEADFED5)
+- Feat: Add `Trait.traithandler` back-reference so custom Traits from the Traits
+  contrib can find and reference other Traits. (Griatch)
 - [Fix][pull3571]: Better visual display of partial multimatch search results
   (InspectorCaracal)
 - [Fix][pull3550]: Issue where rpsystem contrib search would do a global instead

evennia/contrib/rpg/traits/tests.py

@@ -9,10 +9,9 @@ Unit test module for Trait classes.
 from copy import copy
 
 from anything import Something
-from mock import MagicMock, patch
-
 from evennia.objects.objects import DefaultCharacter
 from evennia.utils.test_resources import BaseEvenniaTestCase, EvenniaTest
+from mock import MagicMock, patch
 
 from . import traits
 
@@ -156,6 +155,16 @@ class TraitHandlerTest(_TraitHandlerBase):
             self.obj.attributes.get("traits", category="traits")["test1"]["value"], None
         )
 
+    def test_related_traits(self):
+        """Test traits related to each other via Trait.get_trait()"""
+
+        trait1 = self.traithandler.test1
+        trait2 = self.traithandler.test2
+
+        self.assertEqual(trait1.traithandler, self.traithandler)
+        self.assertEqual(trait1.get_trait("test1"), trait1)
+        self.assertEqual(trait1.get_trait("test2"), trait2)
+
 
 class TestTrait(_TraitHandlerBase):
     """

evennia/contrib/rpg/traits/traits.py

@@ -456,15 +456,9 @@ from functools import total_ordering
 from time import time
 
 from django.conf import settings
-
 from evennia.utils import logger
 from evennia.utils.dbserialize import _SaverDict
-from evennia.utils.utils import (
+from evennia.utils.utils import class_from_module, inherits_from, list_to_string, percent
-    class_from_module,
-    inherits_from,
-    list_to_string,
-    percent,
-)
 
 # Available Trait classes.
 # This way the user can easily supply their own. Each
@@ -657,7 +651,9 @@ class TraitHandler:
         if trait is None and trait_key in self.trait_data:
             trait_type = self.trait_data[trait_key]["trait_type"]
             trait_cls = self._get_trait_class(trait_type)
-            trait = self._cache[trait_key] = trait_cls(_GA(self, "trait_data")[trait_key])
+            trait = self._cache[trait_key] = trait_cls(
+                _GA(self, "trait_data")[trait_key], handler=self
+            )
         return trait
 
     def add(
@@ -856,7 +852,7 @@ class Trait:
     # and have them treated like data to store.
     allow_extra_properties = True
 
-    def __init__(self, trait_data):
+    def __init__(self, trait_data, handler=None):
         """
         This both initializes and validates the Trait on creation. It must
         raise exception if validation fails. The TraitHandler will call this
@@ -869,12 +865,15 @@ class Trait:
                 value in cls.data_default_values. Any extra kwargs will be made
                 available as extra properties on the Trait, assuming the class
                 variable `allow_extra_properties` is set.
+            handler (TraitHandler): The handler that this Trait is connected to.
+                This is for referencing other traits.
 
         Raises:
             TraitException: If input-validation failed.
 
         """
         self._data = self.__class__.validate_input(self.__class__, trait_data)
+        self.traithandler = handler
 
         if not isinstance(trait_data, _SaverDict):
             logger.log_warn(
@@ -955,6 +954,7 @@ class Trait:
             "data_default",
             "trait_type",
             "allow_extra_properties",
+            "traithandler",
         ):
             return _GA(self, key)
         try:
@@ -970,10 +970,9 @@ class Trait:
         """Set extra parameters as attributes.
 
         Arbitrary attributes set on a Trait object will be
-        stored in the 'extra' key of the `_data` attribute.
+        stored as extra keys in the Trait's data.
 
-        This behavior is enabled by setting the instance
+        This behavior is enabled by setting the instance variable `allow_extra_properties`.
-        variable `_locked` to True.
 
         """
         propobj = getattr(self.__class__, key, None)
@@ -984,7 +983,7 @@ class Trait:
             return
         else:
             # this is some other value
-            if key in ("_data",):
+            if key in ("_data", "traithandler"):
                 _SA(self, key, value)
                 return
             if _GA(self, "allow_extra_properties"):
@@ -1053,6 +1052,11 @@ class Trait:
         """Display name for the trait."""
         return self._data["name"]
 
+    def get_trait(self, trait_key):
+        """Get another Trait from the handler. Not used by default, but can be used
+        for custom traits that are affected by other traits on the same handler."""
+        return self.traithandler.get(trait_key)
+
     key = name
 
     # Numeric operations