From a323cdcb33c8c856e5668acfb2c67ab5198672c4 Mon Sep 17 00:00:00 2001
From: Sanyam Khurana <8039608+CuriousLearner@users.noreply.github.com>
Date: Sun, 21 Oct 2018 00:22:02 -0700
Subject: bpo-8525: help() on a type now shows builtin subclasses (GH-5066)

For builtin types with builtin subclasses, help() on the type now shows up
to 4 of the subclasses. This partially replaces the exception hierarchy
information previously displayed in Python 2.7.
---
 Lib/pydoc.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

(limited to 'Lib/pydoc.py')

diff --git a/Lib/pydoc.py b/Lib/pydoc.py
index 8a6b27b16e..3a46171482 100644
--- a/Lib/pydoc.py
+++ b/Lib/pydoc.py
@@ -1254,6 +1254,24 @@ location listed above.
                 push('    ' + makename(base))
             push('')
 
+        # List the built-in subclasses, if any:
+        subclasses = sorted(
+            (str(cls.__name__) for cls in object.__subclasses__()
+             if not cls.__name__.startswith("_") and cls.__module__ == "builtins"),
+            key=str.lower
+        )
+        no_of_subclasses = len(subclasses)
+        MAX_SUBCLASSES_TO_DISPLAY = 4
+        if subclasses:
+            push("Built-in subclasses:")
+            for subclassname in subclasses[:MAX_SUBCLASSES_TO_DISPLAY]:
+                push('    ' + subclassname)
+            if no_of_subclasses > MAX_SUBCLASSES_TO_DISPLAY:
+                push('    ... and ' +
+                     str(no_of_subclasses - MAX_SUBCLASSES_TO_DISPLAY) +
+                     ' other subclasses')
+            push('')
+
         # Cute little class to pump out a horizontal rule between sections.
         class HorizontalRule:
             def __init__(self):
-- 
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