[Python-ideas] Python-ideas Digest, Vol 90, Issue 30

[Antoine Pitrou]

On Wed, 21 May 2014 19:04:58 -0400
Ned Batchelder <ned at nedbatchelder.com>
wrote:
> 
> I'm not sure what can of worms you are imagining.  Let's look to our 
> experience with C compilers.  They have a switch to disable 
> optimization.  What trouble has that brought?  When I think of problems 
> with optimizers in C compilers, I think of incorrect or buggy 
> optimizations.  I can't think of something that has gone wrong because 
> there was a switch to turn it off.

Python's usage model does not contain the notion of compiler
optimizations. Hardly anybody uses the misnamed -O flags. There
is a single compilation mode, which everyone is content with. It is
part of the simplicity of the language (or, at least, of CPython); by
adding some flags than can affect the level of "optimization" you make
the model more complicated to understand for users, and to support for
us.

(having used coverage several times, I haven't found those missed lines
really annoying, by the way; not to the point that I would have wanted
a specific command-line flag to disable optimizations)

The use case for disabling optimizations in C is to make programs
actually debuggable. Python doesn't have that problem.

Regards

Antoine.