[Python-ideas] Adding __getter__ to compliment __iter__.

[Ron Adam]

On 07/19/2013 12:32 PM, Steven D'Aprano wrote:
> On 20/07/13 01:58, Ron Adam wrote:
>
>> Could we have syntax for generators to bypass the method calls?
>>
>>      x = gen[]                 # next
>
> Please no.
>
> What's so special about generators that they should have magic syntax for
> bypassing methods?

Generators are quite special.  Because they suspend and resume, and the 
values that are passed on each yield are limited to a single object in 
followed by a single object out.

> Good uses for syntax include doing things that you can't
> otherwise do, not as a mere alias for a method.

This is what I was trying to convey.


Inside a generator,  a yield expression is the following byte code.

      "x = yield y"

      0 LOAD_FAST                0 (y)
      3 YIELD_VALUE
      4 STORE_FAST               1 (x)


And it's external counter point is...

      "y = g.send(x)"

      0 LOAD_GLOBAL              0 (g)
      3 LOAD_ATTR                1 (send)
      6 LOAD_FAST                0 (x)
      9 CALL_FUNCTION            1 (1 positional, 0 keyword pair)
     12 STORE_FAST               1 (y)


My question is can we make the above to be this?

      0 LOAD_GLOBAL              0 (g)
      6 LOAD_FAST                0 (x)
      9 RESUME_YIELD
     12 STORE_FAST               1 (y)

It avoids the attribute lookup, and passing the values through the function 
call and signature parsing code in ceval.c.

Cheers,
    Ron