[Python-ideas] Method chaining notation

[Steven D'Aprano]

On Mon, Feb 24, 2014 at 09:01:07AM -0600, Ron Adam wrote:

> You would probably see it used more often like this...
> 
>    def names(defaults, pos_names, pos_args, kwds):
>        return  {}.=update(defaults) \
>                  .=update(zip(pos_names, pos_args) \
>                  .=update(kwds)
> 
> 
> Normally .update returns None.  The reason for that is so that it's clear 
> you are mutating an object instead of creating a new one.
> 
> By using .=, it can return self, but still maintain the clarity between 
> mutation and non-mutation.

How does the update method know whether it is being called via . or via 
.= ? I'm trying to understand how you think this is supposed to work, 
and not having much success. Can you give a sketch of how this .= thingy 
is supposed to operate?

> The other alternative is to use a function.  But it would be difficult to 
> get the same behaviour along with the same efficiency.

I don't see how you can compare the efficiency of code that can be 
written now with code that doesn't exist yet. How do you know how 
efficient your __iget_method__ suggestion will be?


-- 
Steven