[Python-3000] PEP 3107 - Function Annotations

[Phillip J. Eby]

At 11:13 AM 1/6/2007 -0800, Tony Lownds wrote:

>On Jan 5, 2007, at 9:18 AM, Phillip J. Eby wrote:
>
>>At 10:53 PM 12/27/2006 -0800, Neal Norwitz wrote:
>>>  * With the modification of MAKE_FUNCTION to be a 32-bit value, this
>>>means that EXTENDED_ARG is now used.  This means that the peephole
>>>optimizer won't work for the outer function.  I think we should
>>>correct this.
>>
>>Why not just follow the MAKE_FUNCTION with the calculation of the
>>annotations, followed by a STORE_ATTR to attach them to the
>>function?  Why do we have to change MAKE_FUNCTION for this?
>>(I.e., can't we just compute the annotation values *after* the
>>function is created, but before it's bound to its name?)
>
>Yes, it's possible, I tried the approach and it was more C code, more
>bytecode, and it ran slower.

...and doesn't require EXTENDED_ARG, doesn't introduce a new 
backward-compatibility issue for PyPy, Psyco, or other bytecode-based tools 
(I'm assuming here we'll want to backport annotations to 2.x) or require 
changes to the optimizer.

The additional bytecode and slowdown, IIUC, amounts to a few stack 
manipulations per annotation; the computation of the annotation values 
themselves should still be the bulk of the time used, unless the values are 
constants.