Overloading

[Johannes Reichel]

Hi!

In C++ you can overload functions and constructors. For example if I have a
class that represents a complex number, than it would be nice if I can
write two seperate constructors

class Complex:

def __init__(self):
self.real=0
self.imag=0

def __init__self(self,r,i):
self.real=r
self.imag=i
How would I do this in python?

And by the way, is it possible to overload operators like +,-,*?

def operator+(self,complex2):
Complex res
res.real=self.real+complex2.real
res.imag=self.imag+complex2.imag

return res
thanks!

[jepler]

On Fri, Dec 09, 2005 at 06:29:12PM +0100, Johannes Reichel wrote:

Hi!

In C++ you can overload functions and constructors. For example if I havea
class that represents a complex number, than it would be nice if I can
write two seperate constructors
Python doesn't support this, but it does support default arguments:
class Complex:
def __init__(self, real=0, imag=0):
self.real = real
self.imag = imag
And by the way, is it possible to overload operators like +,-,*?

def operator+(self,complex2):

The special methods have names like __add__.
http://docs.python.org/ref/numeric-types.html

Jeff

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[Christopher Subich]

Johannes Reichel wrote:

Hi!

In C++ you can overload functions and constructors. For example if I have a
class that represents a complex number, than it would be nice if I can
write two seperate constructors

class Complex:

Please do note, if you want this for the exact use of a Complex class,
Python does have complex arithmetic built-in:

print (0 + 1j)

The other posted points are still valid (and generally applicable).

[Josef Meile]

>>In C++ you can overload functions and constructors. For example if I have a

class that represents a complex number, than it would be nice if I can
write two seperate constructors

Python doesn't support this, but it does support default arguments:

Yes, in part you are right since the python core doesn't include them.
However they can be implemented with decorators:

* Subject: decorators and multimethods
Group: comp.lang.python
Link: http://tinyurl.com/d45ym

Anyway, as you, I also use the default arguments.

Regards
Josef

[Josef Meile]

>>> In C++ you can overload functions and constructors. For example if I

have a
class that represents a complex number, than it would be nice if I can
write two seperate constructors

Python doesn't support this, but it does support default arguments:

Yes, in part you are right since the python core doesn't include them.
However they can be implemented with decorators:

* Subject: decorators and multimethods
Group: comp.lang.python
Link: http://tinyurl.com/d45ym

There is even a better recipe, explained step by step from Guido:
* Five-minute Multimethods in Python
Link: http://tinyurl.com/8ppd6

Regards
Josef