BUG: fix deprecation for Ressources when using old constants

Fixes py-pdf#2697

pypdf/_utils.py

@@ -630,3 +630,54 @@ def __lt__(self, other: Any) -> bool:
                 return False
 
         return len(self.components) < len(other.components)
+
+
+# The following class has been copied from Django:
+# https://github.com/django/django/blob/adae619426b6f50046b3daaa744db52989c9d6db/django/utils/functional.py#L51-L65
+#
+# Original license:
+#
+# ---------------------------------------------------------------------------------
+# Copyright (c) Django Software Foundation and individual contributors.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without modification,
+# are permitted provided that the following conditions are met:
+#
+#     1. Redistributions of source code must retain the above copyright notice,
+#        this list of conditions and the following disclaimer.
+#
+#     2. Redistributions in binary form must reproduce the above copyright
+#        notice, this list of conditions and the following disclaimer in the
+#        documentation and/or other materials provided with the distribution.
+#
+#     3. Neither the name of Django nor the names of its contributors may be used
+#        to endorse or promote products derived from this software without
+#        specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+# ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+# ---------------------------------------------------------------------------------
+class classproperty:
+    """
+    Decorator that converts a method with a single cls argument into a property
+    that can be accessed directly from the class.
+    """
+
+    def __init__(self, method=None):
+        self.fget = method
+
+    def __get__(self, instance, cls=None):
+        return self.fget(cls)
+
+    def getter(self, method):
+        self.fget = method
+        return self

pypdf/constants.py

@@ -14,7 +14,7 @@
 from enum import IntFlag, auto
 from typing import Dict, Tuple
 
-from ._utils import deprecate_with_replacement
+from ._utils import classproperty, deprecate_with_replacement
 
 
 class Core:
@@ -161,50 +161,42 @@ class Ressources:  # deprecated
     .. deprecated:: 5.0.0
     """
 
-    @classmethod  # type: ignore
-    @property
+    @classproperty
     def EXT_G_STATE(cls) -> str:
         deprecate_with_replacement("Ressources", "Resources", "5.0.0")
         return "/ExtGState"  # dictionary, optional
 
-    @classmethod  # type: ignore
-    @property
+    @classproperty
     def COLOR_SPACE(cls) -> str:
         deprecate_with_replacement("Ressources", "Resources", "5.0.0")
         return "/ColorSpace"  # dictionary, optional
 
-    @classmethod  # type: ignore
-    @property
+    @classproperty
     def PATTERN(cls) -> str:
         deprecate_with_replacement("Ressources", "Resources", "5.0.0")
         return "/Pattern"  # dictionary, optional
 
-    @classmethod  # type: ignore
-    @property
+    @classproperty
     def SHADING(cls) -> str:
         deprecate_with_replacement("Ressources", "Resources", "5.0.0")
         return "/Shading"  # dictionary, optional
 
-    @classmethod  # type: ignore
-    @property
+    @classproperty
     def XOBJECT(cls) -> str:
         deprecate_with_replacement("Ressources", "Resources", "5.0.0")
         return "/XObject"  # dictionary, optional
 
-    @classmethod  # type: ignore
-    @property
+    @classproperty
     def FONT(cls) -> str:
         deprecate_with_replacement("Ressources", "Resources", "5.0.0")
         return "/Font"  # dictionary, optional
 
-    @classmethod  # type: ignore
-    @property
+    @classproperty
     def PROC_SET(cls) -> str:
         deprecate_with_replacement("Ressources", "Resources", "5.0.0")
         return "/ProcSet"  # array, optional
 
-    @classmethod  # type: ignore
-    @property
+    @classproperty
     def PROPERTIES(cls) -> str:
         deprecate_with_replacement("Ressources", "Resources", "5.0.0")
         return "/Properties"  # dictionary, optional

tests/test_utils.py

@@ -11,6 +11,7 @@
     _get_max_pdf_version_header,
     _human_readable_bytes,
     check_if_whitespace_only,
+    classproperty,
     deprecate_with_replacement,
     deprecation_no_replacement,
     mark_location,
@@ -424,3 +425,19 @@ def test_version_compare_lt_str():
 
 def test_bad_version():
     assert Version("a").components == [(0, "a")]
+
+
+def test_classproperty():
+    class Container:
+        @classproperty
+        def value1(cls):
+            return 42
+
+        @classproperty
+        def value2(cls):
+            return 1337
+
+    assert Container.value1 == 42
+    assert Container.value2 == 1337
+    assert Container().value1 == 42
+    assert Container().value2 == 1337