Re: [Tutor] Can this be done easly
Roelof Wobben wrote: >> Hint: why does this work: >> >>> def __init__(self, x=0, y=0): >> >> ...while this doesnt: >> >>> def _init_(self, base_point, width=0, length=0): >> >> Peter > Maybe because base_point has no value ? No. One __init__ has two underscores (correct) on each side, the other _init_ only one (wrong). ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Can this be done easly
"Roelof Wobben" wrote When I change everything to this : class Rectangle(object): def _init_(self, base_point, width=0, length=0): self.base_point = base_point self.width = width self.length = length punt = Point(3,4) rechthoek = Rectangle (punt,20,30) I get this message : Traceback (most recent call last): File "C:\Users\wobben\workspace\oefeningen\src\test.py", line 13, in rechthoek = Rectangle (punt,20,30) TypeError: object.__new__() takes no parameters Very odd, but are you using IDLE or a similar IDE? Have you remembered to reload the module? Just a thought... Alan G. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Can this be done easly
> To: tutor@python.org > From: __pete...@web.de > Date: Sun, 19 Sep 2010 18:04:25 +0200 > Subject: Re: [Tutor] Can this be done easly > > Roelof Wobben wrote: > >> When I change everything to this : > >> I get this message : >> >> Traceback (most recent call last): >> File "C:\Users\wobben\workspace\oefeningen\src\test.py", line 13, in >> >> rechthoek = Rectangle (punt,20,30) >> TypeError: object.__new__() takes no parameters > > Hint: why does this work: > >> def __init__(self, x=0, y=0): > > ...while this doesnt: > >> def _init_(self, base_point, width=0, length=0): > > Peter > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor Hoi, Maybe because base_point has no value ? Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Can this be done easly
Roelof Wobben wrote: > When I change everything to this : > I get this message : > > Traceback (most recent call last): > File "C:\Users\wobben\workspace\oefeningen\src\test.py", line 13, in > > rechthoek = Rectangle (punt,20,30) > TypeError: object.__new__() takes no parameters Hint: why does this work: > def __init__(self, x=0, y=0): ...while this doesnt: > def _init_(self, base_point, width=0, length=0): Peter ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Can this be done easly
> Date: Sun, 19 Sep 2010 14:19:46 +0200 > From: knack...@googlemail.com > To: tutor@python.org > Subject: Re: [Tutor] Can this be done easly > > Am 19.09.2010 10:49, schrieb Roelof Wobben: >> >> >> Hello, >> >> I have this programm : >> >> class Point: >> def __init__(self, x=0, y=0): >> self.x = x >> self.y = y >> >> class Rectangle(Point): >> def _init_(self, width=0, length=0): >> self.width = width >> self.length = length > You're inheriting the Point Class, but you don't initialise it. > For some detailled description of inheritance in Python I rather suggest > to check out some tutorials instead of trying to explain it. Also, > others on this list can do this probably better. Here's one reference: > http://diveintopython.org/object_oriented_framework/index.html > > But now some remarks regarding your problem: > > First, I would not consider a Rectangle as a special Point. It's not a > relation like a Sportscar is a Car (is-a-relationship). It's more a > relation a Rectangle has 4 Points (has-a-relationship), or 1 Point and a > width and length. So, it's probably better to express your Rectangle > class like this: > > class Rectangle(object): > def __init__(self, base_point, width=0, length=0): > self.base_point = base_point > self.width = width > self.length = length > > then you go (with German names ;-)): > > punkt = Point(3,4) > rechteck = Rectangle(punkt,20,30) > > In your Rectangle class, the __init__ method takes only two arguments > (not counting the instance: self), but you're passing three arguments. > > At the beginning, the error messages are a bit confusing, because they > count the instance as one of the arguments. So it tells you, that you > have given 4 arguments, but you might wonder "Hey, I gave you 3". > > HTH, > > Jan > >> >> punt = Point(3,4) >> rechthoek = Rectangle (punt,20,30) >> >> Now I wonder how I can change this to rechthoek = rectangle (punt,20,20) >> This one gives as error message : >> >> Traceback (most recent call last): >> File "C:\Users\wobben\workspace\oefeningen\src\test.py", line 12, in >> rechthoek = Rectangle (punt,20,30) >> TypeError: __init__() takes at most 3 arguments (4 given) >> >> Roelof >> >> ___ >> Tutor maillist - Tutor@python.org >> To unsubscribe or change subscription options: >> http://mail.python.org/mailman/listinfo/tutor > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor Hello, When I change everything to this : class Point: def __init__(self, x=0, y=0): self.x = x self.y = y class Rectangle(object): def _init_(self, base_point, width=0, length=0): self.base_point = base_point self.width = width self.length = length punt = Point(3,4) rechthoek = Rectangle (punt,20,30) I get this message : Traceback (most recent call last): File "C:\Users\wobben\workspace\oefeningen\src\test.py", line 13, in rechthoek = Rectangle (punt,20,30) TypeError: object.__new__() takes no parameters Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Can this be done easly
Am 19.09.2010 10:49, schrieb Roelof Wobben: Hello, I have this programm : class Point: def __init__(self, x=0, y=0): self.x = x self.y = y class Rectangle(Point): def _init_(self, width=0, length=0): self.width = width self.length = length You're inheriting the Point Class, but you don't initialise it. For some detailled description of inheritance in Python I rather suggest to check out some tutorials instead of trying to explain it. Also, others on this list can do this probably better. Here's one reference: http://diveintopython.org/object_oriented_framework/index.html But now some remarks regarding your problem: First, I would not consider a Rectangle as a special Point. It's not a relation like a Sportscar is a Car (is-a-relationship). It's more a relation a Rectangle has 4 Points (has-a-relationship), or 1 Point and a width and length. So, it's probably better to express your Rectangle class like this: class Rectangle(object): def __init__(self, base_point, width=0, length=0): self.base_point = base_point self.width = width self.length = length then you go (with German names ;-)): punkt = Point(3,4) rechteck = Rectangle(punkt,20,30) In your Rectangle class, the __init__ method takes only two arguments (not counting the instance: self), but you're passing three arguments. At the beginning, the error messages are a bit confusing, because they count the instance as one of the arguments. So it tells you, that you have given 4 arguments, but you might wonder "Hey, I gave you 3". HTH, Jan punt = Point(3,4) rechthoek = Rectangle (punt,20,30) Now I wonder how I can change this to rechthoek = rectangle (punt,20,20) This one gives as error message : Traceback (most recent call last): File "C:\Users\wobben\workspace\oefeningen\src\test.py", line 12, in rechthoek = Rectangle (punt,20,30) TypeError: __init__() takes at most 3 arguments (4 given) Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
