RE: Unexpected randomseed results (was [ANN] uuid: pure Lua uuid generator)

[Thijs Schreijer <thijs@...>]

> -----Original Message-----
> From: lua-l-bounces@lists.lua.org [mailto:lua-l-bounces@lists.lua.org] On
> Behalf Of Sean Conner
> Sent: zaterdag 11 mei 2013 10:23
> To: Lua mailing list
> Subject: Re: Unexpected randomseed results (was [ANN] uuid: pure Lua uuid
> generator)
> 
> It was thus said that the Great Sean Conner once stated:
> >
> >   In thinking about it, Lua should do the following:
> >
> > 	srand(luaL_checkint(L,1) % INT_MAX);
> 
>   Ooops, that's silly.  What I meant was:
> 
> 	srand((unsigned int)fmod(luaL_checknumber(L,1),UINT_MAX));
> 
>   for both Lua 5.1 and 5.2.
> 
>   Or perhaps:
> 
> 	double       ds = luaL_checknumber(L,1);
> 	unsigned int s;
> 
> 	if (ds < 1.0)
> 	  s = (unsigned int)(ds * (double)UINT_MAX);
> 	else if (ds > UINT_MAX)
>  	  s = (unsigned int)fmod(ds,UINT_MAX);
> 	else
> 	  s = (unsigned int)ds;
> 
> 	srand(ds);
> 
> to force it into a range of 0 .. UINT_MAX.
> 

Nice, but even then, I think a word of warning in the manual would be welcome. Or as mentioned before; simply return the seed as set, so the script can check whether everything is ok.

Thijs

>   -spc (Or just keep it as is and be a bit more careful about seeding)
>