[issue3976] pprint._safe_repr is not general enough in one instance

[Erick Tryzelaar]

Erick Tryzelaar <idadesub at users.sourceforge.net> added the comment:

fyi, I found another case where pprint needs a "safe sort", this is
when you have a list that contains a dictionary. Anyway, Here's a
simple patch that creates a _safe_sorted function that implements the
fallback:

--- /opt/local/lib/python3.0/pprint.py	2008-09-26 09:35:21.000000000 -0700
+++ /tmp/pprint.py	2008-09-26 09:35:13.000000000 -0700
@@ -145,7 +145,7 @@
                 if length:
                     context[objid] = 1
                     indent = indent + self._indent_per_level
-                    items  = sorted(object.items())
+                    items  = _safe_sorted(object.items())
                     key, ent = items[0]
                     rep = self._repr(key, context, level)
                     write(rep)
@@ -267,14 +267,7 @@
         append = components.append
         level += 1
         saferepr = _safe_repr
-        items = object.items()
-        try:
-            items = sorted(items)
-        except TypeError:
-            def sortkey(item):
-                key, value = item
-                return str(type(key)), key, value
-            items = sorted(items, key=sortkey)
+        items = _safe_sorted(object.items())
         for k, v in items:
             krepr, kreadable, krecur = saferepr(k, context, maxlevels, level)
             vrepr, vreadable, vrecur = saferepr(v, context, maxlevels, level)
@@ -321,6 +314,20 @@
     rep = repr(object)
     return rep, (rep and not rep.startswith('<')), False

+def _safe_sorted(items):
+    try:
+        return sorted(items)
+    except TypeError:
+        def sortkey(item):
+            key, value = item
+            return str(type(key)), key, value
+        try:
+            return sorted(items, key=sortkey)
+        except TypeError:
+            def sortkey(item):
+                key, value = item
+                return str(type(key))
+            return sorted(items, key=sortkey)

 def _recursion(object):
     return ("<Recursion on %s with id=%s>"

One other thing to note is that I'm also aware that the yaml project
also has this problem, and they've got their own "safe_sorted"
function. It might be worthwhile formalizing this in a public function
in the api somewhere.

----------
nosy: +idadesub

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue3976>
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