From b1e25d99ab3bcea0e680a5970e7987c3b8badefc Mon Sep 17 00:00:00 2001
From: Thomas Li <thomasli1234567890@gmail.com>
Date: Mon, 27 Jan 2020 19:42:34 -0800
Subject: [PATCH 1/4] Deprecate core

---
 pandas/__init__.py           | 38 ++++++++++++++++++++++++++++++++++++
 pandas/tests/api/test_api.py |  7 ++++---
 2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/pandas/__init__.py b/pandas/__init__.py
index d526531b159b2..8e100b45dd2ef 100644
--- a/pandas/__init__.py
+++ b/pandas/__init__.py
@@ -190,6 +190,10 @@
 # TODO: remove Panel compat in 1.0
 if pandas.compat.PY37:
 
+    import pandas.core as _core
+
+    del pandas.core
+
     def __getattr__(name):
         import warnings
 
@@ -256,6 +260,18 @@ class Panel:
 
             return _SparseArray
 
+        elif name == "core":
+
+            warnings.warn(
+                "The pandas.core module is private and access "
+                "will be moved to pandas._core in a future version. "
+                f"You should import directly from the pandas namespace instead",
+                FutureWarning,
+                stacklevel=2,
+            )
+
+            return _core
+
         raise AttributeError(f"module 'pandas' has no attribute '{name}'")
 
 
@@ -360,6 +376,28 @@ def __new__(cls, *args, **kwargs):
 
     SparseArray = __SparseArraySub
 
+    class __core:
+        def __init__(self):
+            import pandas.core as core
+            import warnings
+
+            self._core = core
+            self._warnings = warnings
+
+        def __getattr__(self, item):
+            attr = getattr(self._core, item)
+            self._warnings.warn(
+                "The pandas.core module is private and access "
+                "will be moved to pandas._core in a future version. "
+                f"You should import pandas.{item} directly instead",
+                FutureWarning,
+                stacklevel=2,
+            )
+            return attr
+
+    _core = __core()
+    core: __core = __core()
+
 
 # module level doc-string
 __doc__ = """
diff --git a/pandas/tests/api/test_api.py b/pandas/tests/api/test_api.py
index 406d5f055797d..8b870df0a0959 100644
--- a/pandas/tests/api/test_api.py
+++ b/pandas/tests/api/test_api.py
@@ -46,7 +46,7 @@ class TestPDApi(Base):
     ]
 
     # these are already deprecated; awaiting removal
-    deprecated_modules: List[str] = ["np", "datetime"]
+    deprecated_modules: List[str] = ["np", "datetime", "core"]
 
     # misc
     misc = ["IndexSlice", "NaT", "NA"]
@@ -190,6 +190,7 @@ class TestPDApi(Base):
     # private modules in pandas namespace
     private_modules = [
         "_config",
+        "_core",
         "_hashtable",
         "_lib",
         "_libs",
@@ -241,11 +242,11 @@ def test_depr(self):
                 deprecated = getattr(pd, depr)
                 if not compat.PY37:
                     if depr == "datetime":
-                        deprecated.__getattr__(dir(pd.datetime.datetime)[-1])
+                        deprecated.__getattr__(dir(pd.datetime.datetime)[0])
                     elif depr == "SparseArray":
                         deprecated([])
                     else:
-                        deprecated.__getattr__(dir(deprecated)[-1])
+                        deprecated.__getattr__(dir(deprecated)[0])
 
 
 def test_datetime():

From 2c29df13d708eb38ef3b1d591ac32a87ef5b9ae8 Mon Sep 17 00:00:00 2001
From: Thomas Li <thomasli1234567890@gmail.com>
Date: Mon, 27 Jan 2020 19:45:24 -0800
Subject: [PATCH 2/4] Fix api test

---
 pandas/tests/api/test_api.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/pandas/tests/api/test_api.py b/pandas/tests/api/test_api.py
index 8b870df0a0959..42b9f8bcbc04c 100644
--- a/pandas/tests/api/test_api.py
+++ b/pandas/tests/api/test_api.py
@@ -33,7 +33,6 @@ class TestPDApi(Base):
         "api",
         "arrays",
         "compat",
-        "core",
         "errors",
         "pandas",
         "plotting",

From 6e229f0416fa248b9742d34d49d7cd9e1f7e6da6 Mon Sep 17 00:00:00 2001
From: Thomas Li <thomasli1234567890@gmail.com>
Date: Mon, 27 Jan 2020 19:49:08 -0800
Subject: [PATCH 3/4] Whatsnew

---
 doc/source/whatsnew/v1.1.0.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v1.1.0.rst b/doc/source/whatsnew/v1.1.0.rst
index 920919755dc23..10dd73d811b5e 100644
--- a/doc/source/whatsnew/v1.1.0.rst
+++ b/doc/source/whatsnew/v1.1.0.rst
@@ -69,7 +69,8 @@ Backwards incompatible API changes
 Deprecations
 ~~~~~~~~~~~~
 
--
+- Access to the ``pandas.core`` submodule is now deprecated, and the module will be moving to ``pandas._core`` in the future.
+  Please import all classes/methods from the top level pandas namespace instead.
 -
 
 .. ---------------------------------------------------------------------------

From 70f0146f3c9da96251dbde107d9b20c32b202b3b Mon Sep 17 00:00:00 2001
From: Thomas Li <thomasli1234567890@gmail.com>
Date: Mon, 27 Jan 2020 20:32:22 -0800
Subject: [PATCH 4/4] Docstring and mypy fixes

---
 pandas/__init__.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/pandas/__init__.py b/pandas/__init__.py
index 8e100b45dd2ef..6d16ec77237af 100644
--- a/pandas/__init__.py
+++ b/pandas/__init__.py
@@ -395,10 +395,9 @@ def __getattr__(self, item):
             )
             return attr
 
-    _core = __core()
+    _core: __core = __core()  # type: ignore
     core: __core = __core()
 
-
 # module level doc-string
 __doc__ = """
 pandas - a powerful data analysis and manipulation library for Python