problems of creating object instances in python

Question

I want to define a class and create an object instance. But always get error. The code goes like this:

class complex:
    def _init_(self,realpart,imagpart):
        self.r=realpart
        self.i=imagpart

x=complex(3,4)

the error message is:

Traceback (most recent call last):<br>
  File "pyshell#5", line 1, in "module" <br>
  x=complex(3,4) <br>
  TypeError: object.__new__() takes no parameters

so what is the problem?

thanks for your reading!

Python has native support for complex numbers. 3+4j for example — John La Rooy
– John La Rooy, Commented Feb 20, 2013 at 4:26

Blender · Accepted Answer · 2013-02-20 04:25:02Z

2

_init_ should have two underscores on each side:

>>> class complex:
...     def __init__(self,realpart,imagpart):
...         self.r=realpart
...         self.i=imagpart
... 
>>> x=complex(3,4)

Also, just so you know, Python already has a complex type:

>>> 2+3j
(2+3j)
>>> complex(2, 3)
(2+3j)

answered Feb 20, 2013 at 4:25

Blender

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Comments

Abhijit · Accepted Answer · 2013-02-20 04:29:12Z

__init__ supposed to have 2 underscores surrounding it rather than 1

So

def _init_(self,realpart,imagpart):

should be

def __init__(self,realpart,imagpart):

One more suggesting, instead of multiple assignments, tuple unpacking would be more readable and marginally efficient
Prefer new Type Class construct, which derives from object
PEP8 suggests to use CamelCase for Class Names
Always use the batteries if available instead of rolling your own. Python already supports complex types by default

SO here it goes

class complex(object):
    def __init__(self,realpart,imagpart):
        self.r, self.i=realpart, imagpart

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