From 81aa933d7c0a55c455d03112578fb5f67bbdda7c Mon Sep 17 00:00:00 2001
From: Laurent Peuch <cortex@worlddomination.be>
Date: Wed, 22 Apr 2020 21:20:09 +0200
Subject: [deprecation/refactoring] start simplifying module and simplify
 class_deprecated

---
 logilab/common/deprecation.py | 59 ++++++++++++++++++++++++++++++++++++++++++-
 test/unittest_deprecation.py  |  2 +-
 2 files changed, 59 insertions(+), 2 deletions(-)

diff --git a/logilab/common/deprecation.py b/logilab/common/deprecation.py
index 4aaeba3..4a14aac 100644
--- a/logilab/common/deprecation.py
+++ b/logilab/common/deprecation.py
@@ -19,6 +19,7 @@
 
 __docformat__ = "restructuredtext en"
 
+import os
 import sys
 from warnings import warn
 from functools import wraps
@@ -178,15 +179,71 @@ class DeprecationManager(object):
                 reason = '[%s] %s' % (version, reason)
             warn(reason, DeprecationWarning, stacklevel=stacklevel)
 
+
 _defaultdeprecator = DeprecationManager()
 
+
+def _get_package_name(number=2):
+    """
+    automagically try to determine the package name from which the warning has
+    been triggered by loop other calling frames.
+
+    If it fails to do so, return an empty string.
+    """
+
+    frame = sys._getframe()
+
+    for i in range(number):
+        if frame.f_back is None:
+            break
+
+        frame = frame.f_back
+
+    if frame.f_globals["__package__"] is not None:
+        return frame.f_globals["__package__"]
+
+    file_name = os.path.split(frame.f_globals["__file__"])[1]
+
+    if file_name.endswith(".py"):
+        file_name = file_name[:-len(".py")]
+
+    return file_name
+
+
+def send_warning(reason, version=None, stacklevel=2):
+    """Display a deprecation message only if the version is older than the
+    compatible version.
+    """
+    module_name = _get_package_name(stacklevel + 1)
+
+    if module_name and version:
+        reason = '[%s %s] %s' % (module_name, version, reason)
+    elif module_name:
+        reason = '[%s] %s' % (module_name, reason)
+    elif version:
+        reason = '[%s] %s' % (version, reason)
+
+    warn(reason, DeprecationWarning, stacklevel=stacklevel)
+
+
 def deprecated(reason=None, stacklevel=2, name=None, doc=None):
     return _defaultdeprecator.deprecated(None, reason, stacklevel, name, doc)
 
-class_deprecated = _defaultdeprecator.class_deprecated()
+
+class class_deprecated(type):
+    """metaclass to print a warning on instantiation of a deprecated class"""
+
+    def __call__(cls, *args, **kwargs):
+        msg = getattr(cls, "__deprecation_warning__",
+                      "%(cls)s is deprecated") % {'cls': cls.__name__}
+        send_warning(msg, stacklevel=4)
+        return type.__call__(cls, *args, **kwargs)
+
 
 def moved(modpath, objname):
     return _defaultdeprecator.moved(None, modpath, objname)
+
+
 moved.__doc__ = _defaultdeprecator.moved.__doc__
 
 
diff --git a/test/unittest_deprecation.py b/test/unittest_deprecation.py
index 60b10f4..a348d67 100644
--- a/test/unittest_deprecation.py
+++ b/test/unittest_deprecation.py
@@ -49,7 +49,7 @@ class RawInputTC(TestCase):
             pass
         AnyClass()
         self.assertEqual(self.messages,
-                         ['AnyClass is deprecated'])
+                         ['[logilab.common] AnyClass is deprecated'])
 
     def test_deprecated_func(self):
         any_func = deprecation.deprecated()(self.mk_func())
-- 
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