Review Request: Convenience KRandom methods

[Thomas Lübking]

> On 2010-08-12 19:17:04, Ingo Klöcker wrote:
> > trunk/KDE/kdelibs/kdecore/util/krandom.cpp, line 55
> > <http://reviewboard.kde.org/r/4992/diff/3/?file=33701#file33701line55>
> >
> >     This will probably crash if you call it with min = MIN_INT and max = MAX_INT because then max-min+1 = 0 (due to an integer overflow). In fact, even smaller ranges will most likely be problematic as soon as max-min+1 > MAX_INT.
> >     
> >     Apart from the integer overflow problem this method will not return uniformly distributed random numbers. See for example http://www.cplusplus.com/reference/clibrary/cstdlib/rand/.
> >     
> >     If you want uniformly distributed random numbers in a certain integer range then use
> >     http://www.boost.org/doc/libs/1_43_0/doc/html/boost_random/tutorial.html#boost_random.tutorial.generating_integers_in_a_range
> >     instead of trying to re-invent a wheel that is much more complicated than you think.
> >     
> >     As far as I'm concerned I'm against adding such a flawed method to kdelibs.
> 
> Sebastian Trueg wrote:
>     And this is exactly why it makes so much sense to put it in kdecode. There are thousands of ways to get this wrong. I only showed two so far. ;)
>     And btw: I do not think this is simple. That is why I want your feedback.
>     I will look at the boost approach and have another go at it.
> 
> Ingo Klöcker wrote:
>     I repeat my question: Why re-invent the wheel? I really don't understand the aversion of many KDE developers against using boost. KDE is mostly written in C++. So why not use some of the best free C++ libraries existing on this planet?

No idea. But random thoughts?
- boost is pretty large and this item is pretty small?
- it itersects with Qt
- it intersects with c++0x (since it partially became part of it, including this item, i think - not sure, though)
(- on windows, M$ has a competitive TR1 implementation... but that doesn't count :)


- Thomas


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On 2010-08-12 13:40:52, Sebastian Trueg wrote:
> 
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> 
> (Updated 2010-08-12 13:40:52)
> 
> 
> Review request for kdelibs.
> 
> 
> Summary
> -------
> 
> The KRandom namespace is quite useful. However, applications need to be full of code snippets that calculate a random number in a range. IMHO it makes perfect sense to do this once in the library. Thus, I am proposing this patch to introduce two methods providing random numbers from a range.
> Feel free to improve the implementation. :)
> 
> 
> Diffs
> -----
> 
>   trunk/KDE/kdelibs/kdecore/util/krandom.h 1162164 
>   trunk/KDE/kdelibs/kdecore/util/krandom.cpp 1162164 
> 
> Diff: http://reviewboard.kde.org/r/4992/diff
> 
> 
> Testing
> -------
> 
> 
> Thanks,
> 
> Sebastian
> 
>

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