Fixes @set to be more accepting of various Python structures. It will now instead convert to string on a ValueError (commonly because a string was not enclosed in quotes) while giving a error string to the user informing of this. This should fix Issue 256.

src/commands/default/building.py

@@ -19,6 +19,13 @@ __all__ = ("ObjManipCommand", "CmdSetObjAlias", "CmdCopy",
            "CmdLock", "CmdExamine", "CmdFind", "CmdTeleport",
            "CmdScript")
 
+try:
+    # used by @set
+    from ast import literal_eval as _LITERAL_EVAL
+except ImportError:
+    # literal_eval is not available before Python 2.6
+    _LITERAL_EVAL = None
+
 # used by @find
 CHAR_TYPECLASS = settings.BASE_CHARACTER_TYPECLASS
 
@@ -1176,11 +1183,19 @@ class CmdSetAttribute(ObjManipCommand):
     def convert_from_string(self, strobj):
         """
         Converts a single object in *string form* to its equivalent python
-        type. Handles floats, ints, and limited nested lists and dicts
+        type.
+
+         Python earlier than 2.6:
+        Handles floats, ints, and limited nested lists and dicts
         (can't handle lists in a dict, for example, this is mainly due to
         the complexity of parsing this rather than any technical difficulty -
         if there is a need for @set-ing such complex structures on the
         command line we might consider adding it).
+         Python 2.6 and later:
+        Supports all Python structures through literal_eval as long as they
+        are valid Python syntax. If they are not (such as [test, test2], ie
+        withtout the quotes around the strings), the entire structure will
+        be converted to a string and a warning will be given.
 
         We need to convert like this since all data being sent over the
         telnet connection by the Player is text - but we will want to
@@ -1191,7 +1206,8 @@ class CmdSetAttribute(ObjManipCommand):
 
         def rec_convert(obj):
             """
-            Helper function of recursive conversion calls.
+            Helper function of recursive conversion calls. This is only
+            used for Python <=2.5. After that literal_eval is available.
             """
             # simple types
             try: return int(obj)
@@ -1211,18 +1227,20 @@ class CmdSetAttribute(ObjManipCommand):
                              for pair in obj[1:-1].split(',') if ":" in pair])
             # if nothing matches, return as-is
             return obj
-        if strobj.strip() and strobj.strip()[0] in ("'", '"', "(", "{ ", "["):
-            # this is a structure starting with a proper python structure,
-            # so treat it as such.
+
+        if _LITERAL_EVAL:
+            # Use literal_eval to parse python structure exactly.
             try:
-                # under python 2.6, literal_eval can do this for us.
-                from ast import literal_eval
-                return literal_eval(strobj)
-            except ImportError:
-                # fall back to old recursive solution (don't support nested lists/dicts)
-                return rec_convert(strobj.strip())
+                return _LITERAL_EVAL(strobj)
+            except ValueError:
+                # treat as string
+                string = "{RNote: Value was converted to string. If you don't want this, "
+                string += "use proper Python syntax, like enclosing strings in quotes.{n"
+                self.caller.msg(string)
+                return utils.to_str(strobj)
         else:
-            return strobj
+            # fall back to old recursive solution (does not support nested lists/dicts)
+            return rec_convert(strobj.strip())
 
     def func(self):
         "Implement the set attribute - a limited form of @py."
@@ -1272,10 +1290,9 @@ class CmdSetAttribute(ObjManipCommand):
                     string += "\nCreated attribute %s/%s = %s" % (obj.name, attr, value)
                 except SyntaxError:
                     # this means literal_eval tried to parse a faulty string
-                    string = "{RPython syntax error in your value. By assigning a value starting with"
-                    string += "\none of {r'{R, {r\"{R, {r[{R, {r({R or {r{{R we assume you are entering a proper Python"
-                    string += "\nprimitive such as a list or a dictionary. You must then also use correct"
-                    string += "\nPython syntax. Remember especially to put quotes around all strings.{n"
+                    string = "{RCritical Python syntax error in your value. Only primitive Python structures"
+                    string += "\nare allowed. You also need to use correct Python syntax. Remember especially"
+                    string += "\nto put quotes around all strings inside lists and dicts.{n"
         # send feedback
         caller.msg(string.strip('\n'))