Software bugs aren't inevitable

phil hunt zen19725 at zen.co.uk
Sat Sep 17 02:17:38 CEST 2005


On Fri, 16 Sep 2005 20:05:04 -0400, Mike Meyer <mwm at mired.org> wrote:
>zen19725 at zen.co.uk (phil hunt) writes:
>> Compilers/interpreters/runtimes are black boxes: we don't (or
>> shouldn't) care how they do their work as long as they run correctly 
>> and aren't too heavy on system resources like CPU time and memory.
>
>Maybe in academia. Not in the real world. Or maybe you just phrased
>that last clause poorly.

I think perhaps I did.

> In the real world, programs have performance
>constraints.

Yes i know, that's why I said "aren't too heavy on system resources 
like CPU time and memory".

> Some of them are seriously inflexible - in which case we
>call what we're doing "real-time" or "embedded" or words to that
>effect. 

If a program is too slow to respond isn't that about "system time"?

>Others are softer, but in the end they matter *very much*. I
>would have phrased that last clause to make reasonableness a
>requirement, rather than making "not unreasonable" the requirement.
>
>Because of that, you have to care about how your implementation
>works. If you don't know how strings work in Python, you tend to write
>O(n^2) algorithms instead of O(n) ones for fundamental
>operations.

What does "CPU time" mean again?

-- 
Email: zen19725 at zen dot co dot uk





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