Python dot-equals (syntax proposal)

[Steven D'Aprano]

On Fri, 30 Apr 2010 12:34:34 -0400, D'Arcy J.M. Cain wrote:

> I assume you mean the former to be analagous to "+=" and friends but I
> am not sure since "." isn't an operator.

It's a de facto operator. If you google on "python dot operator" you will 
find many people who refer to it as such, and attribute lookup can be 
over-ridden at runtime (using __getattribute__, __getattr__, etc.) just 
like operators +, -, * etc.

Also you can do this:

>>> s = "something"
>>> s . upper()
'SOMETHING'
>>> (s+" else") . upper()
'SOMETHING ELSE'

And even apply the dot "operator" to floats and ints, although because of 
the ambiguity with floats you need to be clever:

>>> 1.2.is_integer()
False
>>> 4 .numerator
4


However, dot is not a "real" operator, whatever that means: internally, 
CPython treats it as a delimiter:

http://docs.python.org/reference/lexical_analysis.html#operators


In practice though, I think that's a difference that makes no difference. 
It walks like an operator, it swims like an operator, and it quacks like 
an operator.




-- 
Steven