From 96e7ff5e9ff6362d9a886545869ce4496ca4b0fb Mon Sep 17 00:00:00 2001
From: Keryn Knight <keryn@kerynknight.com>
Date: Fri, 7 Jan 2022 09:29:22 +0000
Subject: [PATCH] =?UTF-8?q?Avoided=20isinstance(=E2=80=A6,=20Variable)=20c?=
 =?UTF-8?q?alls=20in=20FilterExpression.resolve().?=
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By determining the variable type within __init__() instead of resolve()
we can skip an isinstance() check at template runtime. Templates are
executed in production more often than the parse trees themselves,
assuming the cached Loader is used.
---
 django/template/base.py     | 3 ++-
 django/templatetags/i18n.py | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/django/template/base.py b/django/template/base.py
index 0dec9940ab..078be8b383 100644
--- a/django/template/base.py
+++ b/django/template/base.py
@@ -694,9 +694,10 @@ class FilterExpression:
 
         self.filters = filters
         self.var = var_obj
+        self.is_var = isinstance(var_obj, Variable)
 
     def resolve(self, context, ignore_failures=False):
-        if isinstance(self.var, Variable):
+        if self.is_var:
             try:
                 obj = self.var.resolve(context)
             except VariableDoesNotExist:
diff --git a/django/templatetags/i18n.py b/django/templatetags/i18n.py
index 8c123c7dd5..607ceb6aea 100644
--- a/django/templatetags/i18n.py
+++ b/django/templatetags/i18n.py
@@ -77,6 +77,7 @@ class TranslateNode(Node):
         self.message_context = message_context
         self.filter_expression = filter_expression
         if isinstance(self.filter_expression.var, str):
+            self.filter_expression.is_var = True
             self.filter_expression.var = Variable("'%s'" %
                                                   self.filter_expression.var)