From 551f2cc0e04bdb4ed22edfc1541a705c4c6d6715 Mon Sep 17 00:00:00 2001
From: Dave Witte Morris <Dave.Morris@uleth.ca>
Date: Tue, 6 Jul 2021 19:38:16 -0600
Subject: [PATCH 1/2] trac 32148 length of propositional formula

---
 src/sage/logic/boolformula.py | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/sage/logic/boolformula.py b/src/sage/logic/boolformula.py
index 5bc168d8404..8af231ca111 100644
--- a/src/sage/logic/boolformula.py
+++ b/src/sage/logic/boolformula.py
@@ -1508,9 +1508,9 @@ def get_next_op(self, str):
             i += 1
         return str[i]
 
-    def __len__(self):
+    def length(self):
         r"""
-        Return the length of a Boolean formula.
+        Return the length of ``self``.
 
         OUTPUT:
 
@@ -1521,37 +1521,40 @@ def __len__(self):
 
             sage: import sage.logic.propcalc as propcalc
             sage: s = propcalc.formula("a")
-            sage: len(s)
+            sage: s.length()
             1
             sage: s = propcalc.formula("(a)")
-            sage: len(s)
+            sage: s.length()
             1
             sage: s = propcalc.formula("~a")
-            sage: len(s)
+            sage: s.length()
             2
             sage: s = propcalc.formula("a -> b")
-            sage: len(s)
+            sage: s.length()
             3
             sage: s = propcalc.formula("alpha -> beta")
-            sage: len(s)
+            sage: s.length()
             3
             sage: s = propcalc.formula("a -> a")
-            sage: len(s)
+            sage: s.length()
             3
             sage: s = propcalc.formula("~(a -> b)")
-            sage: len(s)
+            sage: s.length()
             4
             sage: s = propcalc.formula("((a&b)|(a&c))->~d")
-            sage: len(s)
+            sage: s.length()
             10
 
         TESTS::
 
             sage: s = propcalc.formula("(((alpha) -> ((beta))))")
-            sage: len(s)
+            sage: s.length()
             3
         """
         return len(flatten(self.full_tree()))
 
+    from sage.misc.superseded import deprecated_function_alias
+    __len__ = deprecated_function_alias(32148, length)
+
 # allow is_consequence to be called as a function (not only as a method of BooleanFormula)
 is_consequence = BooleanFormula.is_consequence

From 59cc054aed61866b2fbdfd72b7d5c9d1405956d3 Mon Sep 17 00:00:00 2001
From: Dave Witte Morris <Dave.Morris@uleth.ca>
Date: Thu, 8 Jul 2021 22:49:24 -0600
Subject: [PATCH 2/2] do not deprecate __len__

---
 src/sage/logic/boolformula.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/sage/logic/boolformula.py b/src/sage/logic/boolformula.py
index 8af231ca111..bfaa37739dc 100644
--- a/src/sage/logic/boolformula.py
+++ b/src/sage/logic/boolformula.py
@@ -1553,8 +1553,9 @@ def length(self):
         """
         return len(flatten(self.full_tree()))
 
-    from sage.misc.superseded import deprecated_function_alias
-    __len__ = deprecated_function_alias(32148, length)
+    # For backward compatibility, we allow `self.length()` to be called as
+    # `len(self)`, but this may be deprecated in the future (see :trac:`32148`):
+    __len__ = length
 
 # allow is_consequence to be called as a function (not only as a method of BooleanFormula)
 is_consequence = BooleanFormula.is_consequence