+= overloading?

[Don O'Donnell]

Neil Macneale wrote:
> 
> I am creating a colored stringbuffer class, and I want to append words to
> the buffer with the '+=' operator.  Ex:
> 
> >>>csb = CSB("INIT STRING")
> >>>csb += "Hello"
> >>>print csb
> INIT STRINGHello
> 
> would be the desired effect.  I can't seem to find anything in the lib
> docs about overloading that operator though.  Am I looking in the wrong
> place?  It is also important that a new object is NOT created every time
> the operator is used, because that would be a waste.
> 
> Suggestions?  Thanks for any tips!
> 
> Neil Macneale
> 
> --
> To reply to me via email, remove the '-devnull' from my address.

It's in the Reference Manual, section 3.3.6 in Release 2.1, not the 
Lib docs, since it's an operator defined by the language, not the 
library.

The method you're looking for is called augmented addition, and it 
is defined as: 
        def __iadd__(self, other):
            ...
            return self

In general, the augmented arithmetic operators should update self 
in place where possible.  In the case where self is immutable, as
yours may be since it's string based, you'll have to create a new
concatenated string and rebind self to it.  These methods must also 
return self, since just rebinding the local copy of the self ref 
will never be seen by the caller.

Good luck.

-Don