Added listinstance.py

Author: progrmoiz

listinstance.py

@@ -0,0 +1,54 @@
+#!/usr/bin/env python3
+# File listinstance.py (2.x + 3.x)
+
+from __future__ import print_function
+
+
+class ListInstance:
+    """
+    Mix-in class that provides a formatted print() or str() of instances via
+    inheritance of __str__ coded here; displays instance attrs only; self is
+    instance of lowest class; __X names avoid clashing with client's attrs
+    """
+
+    def __attrnames(self):
+        result = ''
+        for attr in sorted(self.__dict__):
+            result += '\t%s=%s\n' % (attr, self.__dict__[attr])
+        return result
+
+    def __str__(self):
+        return '<Instance of %s, address %s:\n%s>' % (
+            self.__class__.__name__,
+            id(self),
+            self.__attrnames())
+
+
+def tester(listerclass, sept=False):
+
+    class Super:
+
+        def __init__(self):
+            self.data1 = 'spam'
+
+        def ham(self):
+            pass
+
+    class Sub(Super, listerclass):
+
+        def __init__(self):
+            Super.__init__(self)
+            self.data2 = 'eggs'
+            self.data3 = 42
+
+        def spam(self):
+            pass
+
+    instance = Sub()
+    print(instance)
+    if sept:
+        print('-' * 80)
+
+if __name__ == '__main__':
+
+    tester(ListInstance)