Use a custom Jinja2 Context class rather than a custom Template class (…

…#1439)

betty/extension/cotton_candy/assets/templates/entity/label--person-name.html.j2

@@ -1,4 +1,4 @@
-{% import 'macro/citation.html.j2' as citation_macros %}
+{% import 'macro/citation.html.j2' as citation_macros with context %}
 {% set person_name = person_name | default(entity) %}
 {% set embedded = embedded | default(False) %}
 {% set person_context = entity_contexts['Person'] %}

betty/extension/cotton_candy/assets/templates/event-dimensions.html.j2

@@ -1,4 +1,4 @@
-{%- import 'macro/citation.html.j2' as citation_macros -%}
+{%- import 'macro/citation.html.j2' as citation_macros with context -%}
 {%- set embedded = embedded | default(False) -%}
 {%- set citation_context = entity_contexts['Citation'] -%}
 {%- set place_context = entity_contexts['Place'] -%}

betty/jinja2/__init__.py

@@ -6,9 +6,10 @@
 
 import datetime
 from collections import defaultdict
+from collections.abc import MutableMapping, Iterator
 from pathlib import Path
 from threading import Lock
-from typing import Callable, Any, cast, Mapping, TypeVar
+from typing import Callable, Any, cast, TypeVar
 
 import aiofiles
 from aiofiles import os as aiofiles_os
@@ -17,9 +18,8 @@
     select_autoescape,
     FileSystemLoader,
     pass_context,
-    Template as Jinja2Template,
 )
-from jinja2.runtime import StrictUndefined, Context, DebugUndefined, new_context
+from jinja2.runtime import StrictUndefined, Context, DebugUndefined
 
 from betty.app import App
 from betty.html import CssProvider, JsProvider
@@ -155,32 +155,7 @@ def tests(self) -> dict[str, Callable[..., bool]]:
         return {}
 
 
-class Template(Jinja2Template):
-    environment: Environment
-
-    def new_context(
-        self,
-        vars: dict[str, Any] | None = None,
-        shared: bool = False,
-        locals: Mapping[str, Any] | None = None,
-    ) -> Context:
-        return new_context(
-            self.environment,
-            self.name,
-            self.blocks,
-            vars,
-            shared,
-            {
-                "citer": _Citer(),
-                "breadcrumbs": _Breadcrumbs(),
-                **self.globals,
-            },
-            locals,
-        )
-
-
 class Environment(Jinja2Environment):
-    template_class = Template
     globals: dict[str, Any]
     filters: dict[str, Callable[..., Any]]
     tests: dict[str, Callable[..., bool]]
@@ -205,6 +180,7 @@ def __init__(self, app: App):
             ],
         )
 
+        self._context_class: type[Context] | None = None
         self.app = app
 
         if app.project.configuration.debug:
@@ -225,6 +201,35 @@ def _init_i18n(self) -> None:
         )
         self.policies["ext.i18n.trimmed"] = True
 
+    @property
+    def context_class(self) -> type[Context]:  # type: ignore[override]
+        if self._context_class is None:
+
+            class _Context(Context):
+                def __init__(
+                    self,
+                    environment: Environment,
+                    parent: dict[str, Any],
+                    name: str | None,
+                    blocks: dict[str, Callable[[Context], Iterator[str]]],
+                    globals: MutableMapping[str, Any] | None = None,
+                ):
+                    if "citer" not in parent:
+                        parent["citer"] = _Citer()
+                    if "breadcrumbs" not in parent:
+                        parent["breadcrumbs"] = _Breadcrumbs()
+                    super().__init__(
+                        environment,
+                        parent,
+                        name,
+                        blocks,
+                        globals,
+                    )
+
+            self._context_class = _Context
+
+        return self._context_class
+
     @pass_context
     def _gettext(self, context: Context, message: str) -> str:
         return context_localizer(context).gettext(message)
@@ -280,9 +285,6 @@ def _init_extensions(self) -> None:
                 self.tests.update(extension.tests)
 
 
-Template.environment_class = Environment
-
-
 class Jinja2Renderer(Renderer):
     def __init__(self, environment: Environment, configuration: ProjectConfiguration):
         self._environment = environment