Re: [Boost-users] [random] Singleton engine

Subject: Re: [Boost-users] [random] Singleton engine
From: Diederick C. Niehorster (dcnieho_at_[hidden])
Date: 2009-07-26 03:22:08

Thanks Robert,

Your singleton makes stuff really easy.

For those interested, code below works like a breeze. Destructor is
also called at program exit, so no leaks will occur.

Best,
Diederick
---
#pragma once
// includes
#include <boost/random.hpp>
#include <boost/serialization/singleton.hpp>
#include <time.h>
using namespace std;
namespace bs  = boost::serialization;
// declaration
template<class Dist>
class CRandom
{
public:
    /** use for Dist:
        CRandomI Ci(min,max);   uses uniform_int<int>       - integral types
        CRandomR Cr(min,max);   uses uniform_real<double>   - floating
point types
        for other ditributions or types, use:
        CRandom<distribution<optional type>> Cr(0--3 params, depending
on distribution);
        for distributions and params, see:
http://www.boost.org/doc/libs/1_39_0/libs/random/random-distributions.html
        engine is wrapped following singleton pattern, so every instantiation
        of CRandom uses the same engine. Singleton of boost::serialization used
    */
    // forwarding constructors
    explicit CRandom()
        : Gen(bs::singleton<boost::mt19937>::get_mutable_instance(), Dist())
    { }
    template<class P>
    explicit CRandom(const P & p1)
        : Gen(bs::singleton<boost::mt19937>::get_mutable_instance(), Dist(p1))
    { }
    template<class P>
    explicit CRandom(const P & p1, const P & p2)
        : Gen(bs::singleton<boost::mt19937>::get_mutable_instance(),
Dist(p1, p2))
    { }
    template<class P>
    explicit CRandom(const P & p1, const P & p2, const P & p3)
        : Gen(bs::singleton<boost::mt19937>::get_mutable_instance(),
Dist(p1, p2, p3))
    { }
    ~CRandom(void) {};
    typedef typename Dist::result_type result_type;
    result_type operator()() { return Gen(); }
    template<class T>
    result_type operator()(T value) { return Gen(value); }
private:
    boost::variate_generator<boost::mt19937&,Dist> Gen;
};
// end declaration
// shorthand typedefs
typedef CRandom<boost::uniform_int<int>>        CRandomI; // even int
is default type   , specify it in case it ever changes
typedef CRandom<boost::uniform_real<double>>    CRandomR; // even
double is default type, specify it in case it ever changes
On Sun, Jul 26, 2009 at 1:54 PM, Diederick C.
Niehorster<dcnieho_at_[hidden]> wrote:
> Dear Robert,
> Thanks! I will look into
> http://www.boost.org/doc/libs/1_39_0/libs/serialization/doc/singleton.html,
> I should not be reinventing the wheel ;)
>
> Dear Steven,
> Sharp eye, good point. Now two different numbers get generated and all
> those destructor calls dissapeared.
>
> It seems one too many dissapeared even (see program output below).
> Even though MSVC does not complain about memory leaks, at end of
> program the destructor never gets called. Lets see if Robert's
> singleton class solves this, otherwise i suppose i should look into
> using scoped_ptr?
>
> Thanks a lot for your replies,
> Diederick
>
> ------ output:
> check 0
> 00000000
> ctor 1
> after ctor 1
> 003462E0
> random: 8148
> dtor 1
> ctor 2
> after ctor 2
> 003462E0
> random: 1355
> Press any key to continue . . .
>
> On Sun, Jul 26, 2009 at 1:16 PM, Steven Watanabe<watanabesj_at_[hidden]> wrote:
>> AMDG
>>
>> Diederick C. Niehorster wrote:
>>>
>>> template<class Dist>
>>> class CRandom
>>> {
>>> public:
>>> <snip>
>>> private:
>>> Â  Â boost::variate_generator<boost::mt19937,Dist> Gen;
>>> };
>>
>> This copies the engine. Â Try
>> boost::variate_generator<boost::mt19937&,Dist>
>>
>> In Christ,
>> Steven Watanabe
>>
>> _______________________________________________
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>> Boost-users_at_[hidden]
>> http://lists.boost.org/mailman/listinfo.cgi/boost-users
>>
>