Patch to add class level attributes for error_css_class and required_css_class

class.patch

commit 554a7430a2947f67e2316a6775654c66070d75a2
Author: David Smith <smithdc@gmail.com>
Date:   Tue Oct 26 15:55:57 2021 +0100

    Sample class attribute patch

diff --git a/django/forms/boundfield.py b/django/forms/boundfield.py
index 5bbfcbe41c..a971407d0c 100644
--- a/django/forms/boundfield.py
+++ b/django/forms/boundfield.py
@@ -170,7 +170,7 @@ class BoundField:
             id_for_label = widget.id_for_label(id_)
             if id_for_label:
                 attrs = {**(attrs or {}), 'for': id_for_label}
-            if self.field.required and hasattr(self.form, 'required_css_class'):
+            if self.field.required and self.form.required_css_class:
                 attrs = attrs or {}
                 if 'class' in attrs:
                     attrs['class'] += ' ' + self.form.required_css_class
@@ -191,9 +191,9 @@ class BoundField:
         if hasattr(extra_classes, 'split'):
             extra_classes = extra_classes.split()
         extra_classes = set(extra_classes or [])
-        if self.errors and hasattr(self.form, 'error_css_class'):
+        if self.errors and self.form.error_css_class:
             extra_classes.add(self.form.error_css_class)
-        if self.field.required and hasattr(self.form, 'required_css_class'):
+        if self.field.required and self.form.required_css_class:
             extra_classes.add(self.form.required_css_class)
         return ' '.join(extra_classes)
 
diff --git a/django/forms/forms.py b/django/forms/forms.py
index 589b4693fd..339affc262 100644
--- a/django/forms/forms.py
+++ b/django/forms/forms.py
@@ -62,6 +62,8 @@ class BaseForm(RenderableFormMixin):
     field_order = None
     prefix = None
     use_required_attribute = True
+    error_css_class = None
+    required_css_class = None
 
     template_name = 'django/forms/default.html'
     template_name_p = 'django/forms/p.html'

very small changes it seems.

I like the change: both for helping PyCharm / other tooling and for showing easier upfront what is expected instead of spread in the code with hasattrs and getattrs.