__iadd__ and fellows missing (Python 2.2)

[Carey Evans]

On Sun, 14 Apr 2002 09:53:56 +1200, quoth Ralf Juengling,

> Can anybody explain why the special method 'i.__iadd__' does not exist,
> while 'i+=1' is a legal expression ('i' being a int)?

In the absence of __iadd__, += uses __add__ instead.  The end result is
similar to:

    try:
        iadd = x.__iadd__
    except AttributeError:
        iadd = x.__add__
    x = iadd(y)

There's a bit more logic to enable addition of different types (e.g. int
with float) which is described in the reference manual at:

    http://www.python.org/doc/current/ref/numeric-types.html

-- 
	 Carey Evans  http://home.clear.net.nz/pages/c.evans/

			     Cave canem.