[Python-ideas] Disable all peephole optimizations

[Ethan Furman]

On 05/22/2014 08:41 AM, Steve Dower wrote:
> Guido van Rossum wrote:
>>
>> FWIW, I am strictly with Ned here.
>
> As someone who maintains/develops a debugger for Python, I’m with
>  Ned as well (and also Raymond, since I really don’t want to have
>  to worry about one-more-mode that Python might be running in).
>
> Why not move the existing optimisation into -O mode and put future
>  optimisations in there too? It may just start having enough value
>  that people switch to using it.

I will admit to being very surprised the day I realized that the normal run mode for python is debugging mode!

For anyone who hasn't yet realized this, without -O, __debug__ is True, but with any -O __debug__ is False.  Given that, 
it does seem kind of odd to have source altering optimizations active when __debug__ is True.

Of course, we can't change that mid-3.x stream.

However, we could turn off optimizations by default, and then have -O remove assertions /and/ turn on optimizations.

Which would still work nicely with .pyc and .pyo files as ... wait, let me make a table:

  flag   |  optimizations     |  saved files
--------+--------------------+--------------
   none  |    none            |    none
--------+--------------------+--------------
   -O    | asserts removed    |   .pyc
         | peephole, etc.     |
--------+--------------------+--------------
   -OO   | -O plus            |
         | docstrings removed |   .pyo

That would certainly make the -O flags make more sense than they do now.  It would also emphasize the fact that assert 
is not for user data verification.  ;)

--
~Ethan~