//---------------------------------------------------------------------------
/*
Lazy_init. Class to postpone constructor call upon first use.
Copyright (C) 2012-2015 Richel Bilderbeek
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
//---------------------------------------------------------------------------
//From http://www.richelbilderbeek.nl/CppLazy_init.htm
//---------------------------------------------------------------------------
#ifndef LAZY_INIT_H
#define LAZY_INIT_H
#include <string>
#include <vector>
#include <boost/scoped_ptr.hpp>
namespace ribi {
/*
//How to do this with variadic function templates???
template <class T, typename ... Args> struct LazyInit
{
LazyInit(const Args ... args)
: m_args(args)
{
}
const T& Get() const
{
if(!m_data)
{
m_data.reset(new T(m_args));
}
return *m_data;
}
private:
Args ... m_args;
mutable boost::scoped_ptr<T> m_data;
};
*/
template <class T> struct LazyInit0
{
LazyInit0() : m_data{} {}
const T& Get() const
{
if(!m_data)
{
m_data.reset(new T);
}
return *m_data;
}
private:
mutable boost::scoped_ptr<T> m_data;
};
template <class T, typename Arg0> struct LazyInit1
{
LazyInit1(const Arg0 args)
: m_args{args},
m_data{}
{
}
const T& Get() const
{
if(!m_data)
{
m_data.reset(new T(m_args));
}
return *m_data;
}
private:
mutable Arg0 m_args;
mutable boost::scoped_ptr<T> m_data;
};
template <class T, typename Arg0, typename Arg1> struct LazyInit2
{
LazyInit2(const Arg0 arg0, const Arg1 arg1)
: m_arg0{arg0},
m_arg1{arg1},
m_data{}
{
}
const T& Get() const
{
if(!m_data)
{
m_data.reset(new T(m_arg0,m_arg1));
}
return *m_data;
}
private:
mutable Arg0 m_arg0;
mutable Arg1 m_arg1;
mutable boost::scoped_ptr<T> m_data;
};
struct Lazy_initVersion
{
///Obtain the version of this class
static std::string GetVersion() noexcept;
///Obtain the version history of this class
static std::vector<std::string> GetVersionHistory() noexcept;
};
} //~namespace ribi
#endif // LAZY_INIT_H
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