Add and/or alternative and why it doesn't always work.

Correct origin of ?: and ?! again.

pep-0308.txt

@@ -59,6 +59,15 @@ Proposal
         x if C else y, z          <==> (x if C else y), z
         x, y if C else z          <==> x, (y if C else z)
 
+    Note: a common way to emulate an if-then-else expression is:
+
+        <condition> and <expression1> or <expression2>
+
+    However, this doesn't work the same way: it returns <expression2>
+    when <expression1> is false!  See FAQ 4.16 for alternatives that
+    work -- however, they are pretty ugly and require much more
+    effort to understand.
+
 
 Alternatives
 
@@ -66,15 +75,15 @@ Alternatives
 
         <condition> ? <expression1> : <expression2>
 
-    I reject this for several reasons: the colon already has many uses
-    in Python (even though it would actually not be ambiguous, because
-    the question mark requires a matching colon); for people not used
-    to C-derived language, it is hard to understand.
+    Eric Raymond even implemented this.  I reject this for several
+    reasons: the colon already has many uses in Python (even though it
+    would actually not be ambiguous, because the question mark
+    requires a matching colon); for people not used to C-derived
+    language, it is hard to understand.
 
     ---
 
-    David Ascher proposed, and Eric Raymond even implemented, a
-    variant that doesn't have this problem:
+    David Ascher proposed a variant that doesn't have this problem:
 
         <condition> ? <expression1> ! <expression2>
 
@@ -141,8 +150,8 @@ Variations
 
         x = e if C
 
-    to several people and they all thought that if C was false, it
-    would leave x unchanged.  So don't even think about this one!
+    to several people.  They all thought that if C was false, it would
+    leave x unchanged.  So don't even think about this one!
 
 
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