Question

WARNING: I have been learning Python for all of 10 minutes so apologies for any stupid questions!

I have written the following code, however I get the following exception:

Message File Name Line Position Traceback Node 31 exceptions.TypeError: this constructor takes no arguments

class Computer:      name = 'Computer1'     ip = '0.0.0.0'     screenSize = 17       def Computer(compName, compIp, compScreenSize):         name = compName         ip = compIp         screenSize = compScreenSize          printStats()          return      def Computer():         printStats()          return      def printStats():         print 'Computer Statistics: --------------------------------'         print 'Name:' + name         print 'IP:' + ip         print 'ScreenSize:' , screenSize // cannot concatenate 'str' and 'tuple' objects         print '-----------------------------------------------------'         return  comp1 = Computer() comp2 = Computer('The best computer in the world', '27.1.0.128',22) 

Any thoughts?

Answer 1

I’m going to assume you’re coming from a Java-ish background, so there are a few key differences to point out.

class Computer(object):     '''Docstrings are used kind of like Javadoc to document classes and     members.  They are the first thing inside a class or method.      You probably want to extend object, to make it a 'new-style' class.     There are reasons for this that are a bit complex to explain.'''      # everything down here is a static variable, unlike in Java or C# where     # declarations here are for what members a class has.  All instance     # variables in Python are dynamic, unless you specifically tell Python     # otherwise.     defaultName = 'belinda'     defaultRes = (1024, 768)     defaultIP = '192.168.5.307'      def __init__(self, name=defaultName, resolution=defaultRes, ip=defaultIP):         '''Constructors in Python are called __init__.  Methods with names         like __something__ often have special significance to the Python         interpreter.          The first argument to any class method is a reference to the current         object, called 'self' by convention.          You can use default function arguments instead of function         overloading.'''         self.name = name         self.resolution = resolution         self.ip = ip         # and so on      def printStats(self):         '''You could instead use a __str__(self, ...) function to return this         string.  Then you could simply do 'print(str(computer))' if you wanted         to.'''         print 'Computer Statistics: --------------------------------'         print 'Name:' + self.name         print 'IP:' + self.ip         print 'ScreenSize:' , self.resolution //cannot concatenate 'str' and 'tuple' objects         print '-----------------------------------------------------'