Peter Otten wrote: > chandan kumar wrote: > >> Hi , >> >> I'm new to python ,please correct me if there is any thing wrong with the >> way accessing class attributes. >> >> Please see the below code .I have inherited confid in ExpectId class, >> changed self.print_msg to Hello. Now inherited confid in TestprintmsgID >> class.Now I wanted to print self.print_msg value (which is changed under >> ExpectId class) as Hello under TestprintmsgID. I end up with error >> saying >> TestprintmsgID has no attribute self.print_msg. Atleast i expect the >> null to be printed. >> >> >> >> class confid(): >> def __init__(self): >> self.print_msg = "" >> >> class ExpectId(confid): >> >> def __init__(self): >> self.print_msg = " Hello" >> >> def expectmethod(self): >> print "self.print_mesg = ",self.print_msg >> >> class TestprintmsgID(confid): >> >> def __init__(self): >> "Created Instance" >> >> def printmsgmethod(self): >> print "printmsgmethod print_msg val = ",self.print_msg---- Here >> is >> the Attribute error > > If the class has an __init__() method the initializer of the base class is > not invoked automatically. > > In the above code the initializer of TestprintmsgId does nothing, so you > can avoid it. ExpectId.__init__() however must invoke confid.__init_(). > > The complete example:
Sorry, my examples don't show what I wanted to show. I assumed a class hierarchy confid <-- ExpectId <-- TestprintmsgId Also, ExpectId.__init__() need not invoke confid.__init__() in this particular case because both set the same attribute. The general ideas however still stand: (1) if you write an __init__() method it should invoke the __init__() method of the baseclass. (2) omit no-op __init__() methods altogether. Again, sorry for the confusion! -- https://mail.python.org/mailman/listinfo/python-list
