[Python-ideas] Dynamic code NOPing

[Ned Batchelder]

On 12/25/2012 6:04 PM, anatoly techtonik wrote:
> > logger.debug(Message(factorial, 2, 15))
>
> > With this setup, no if statements are needed in your code, and the 
> expensive
> > computations only occur when required.
>
> That's still two function calls and three assignments per logging 
> call. Too expensive and syntax unwieldy. I think everybody agrees now 
> that for existing CPython implementation there is really no solution 
> for the problem of expensive logging calls vs code clarity. You have 
> to implement optimization workaround at the cost of readability.

Anatoly, do you have some measurements to justify the "too expensive" 
claim?  Also, do you have an actual example of expensive logging?  I 
doubt your real code is logging the factorial of 2**15.   What is 
actually in your debug log that is expensive?  It will be much easier to 
discuss solutions if we are talking about actual problems.

>
> The idea is to fix the interpreter, introducing a "feature block" - 
> execution block that works only if it is enabled. Execution block 
> for logging example below is defined by function name "debug" and 
> braces ().
>
>     debug( <block contents> )
>
> debug is an object of 'feature' type, which is only 
> executed/evaluated, if the feature is enabled in a table of features.
>

This feels both sketchy and strange, and not at all integrated with 
existing Python semantics.

--Ned.