Question

class Adder:

    result = 0

    def __init__( self, number1, number2 ):
        self.result = int( number1 ) + int( number2 )

    def giveResult( self ):
        return str(self.result)

class AdderGui:

    def __init__( self ):
        self.builder = gtk.Builder()
        self.builder.add_from_file("Adder.glade")

    def add(self, widget):
        entry1 = self.builder.get_object ("entry1")
        entry2 = self.builder.get_object ("entry2")
        try:
            thistime = adder( entry1.get_text(), entry2.get_text() )
        except ValueError:
            self.builder.get_object("hboxWarning").show()
            self.builder.get_object("entryResult").set_text("ERROR")
            return 0

    def quit(self, widget):
        sys.exit(0)

what i don’t understand here how does thistime variable gets the value of addition. Since init always return none it should not get the value of addition.

Answer 1

It doesn’t. thistime is assigned an Adder object. To get the result, you’ll need to call its giveResult() method. For example:

result = thistime.giveResult()

By the way, class names should by convention be capitalized. Also, result = 0 doesn’t seem to make much sense in the Adder class definition. Object variable self.result is assigned in __init__().