Implement #15

PythonHome/Lib/lib2to3/fixes/fix_sys_exc.py

@@ -0,0 +1,30 @@
+"""Fixer for sys.exc_{type, value, traceback}
+
+sys.exc_type -> sys.exc_info()[0]
+sys.exc_value -> sys.exc_info()[1]
+sys.exc_traceback -> sys.exc_info()[2]
+"""
+
+# By Jeff Balogh and Benjamin Peterson
+
+# Local imports
+from .. import fixer_base
+from ..fixer_util import Attr, Call, Name, Number, Subscript, Node, syms
+
+class FixSysExc(fixer_base.BaseFix):
+    # This order matches the ordering of sys.exc_info().
+    exc_info = [u"exc_type", u"exc_value", u"exc_traceback"]
+    BM_compatible = True
+    PATTERN = """
+              power< 'sys' trailer< dot='.' attribute=(%s) > >
+              """ % '|'.join("'%s'" % e for e in exc_info)
+
+    def transform(self, node, results):
+        sys_attr = results["attribute"][0]
+        index = Number(self.exc_info.index(sys_attr.value))
+
+        call = Call(Name(u"exc_info"), prefix=sys_attr.prefix)
+        attr = Attr(Name(u"sys"), call)
+        attr[1].children[0].prefix = results["dot"].prefix
+        attr.append(Subscript(index))
+        return Node(syms.power, attr, prefix=node.prefix)