singleton: add trivial implementation

This commit is contained in:
Danny Robson 2018-03-22 15:06:48 +11:00
parent 9bfefb3dab
commit 40da3f8df7
3 changed files with 75 additions and 0 deletions

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@ -361,6 +361,7 @@ list (
signal.cpp
signal.hpp
si.hpp
singleton.hpp
stats.cpp
stats.hpp
stream.cpp
@ -525,6 +526,7 @@ if (TESTS)
roots/bisection
sarray
signal
singleton
stream
string
stringid

59
singleton.hpp Normal file
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@ -0,0 +1,59 @@
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Copyright 2018 Danny Robson <danny@nerdcruft.net>
*/
#ifndef CRUFT_UTIL_SINGLETON_HPP
#define CRUFT_UTIL_SINGLETON_HPP
#include "debug.hpp"
#include <memory>
namespace util {
template <typename SelfT>
class singleton {
private:
singleton () = default;
static SelfT *instance;
public:
template <typename ...Args>
static std::unique_ptr<SelfT>
instantiate [[nodiscard]] (Args &&...args)
{
CHECK (!instance);
auto cookie =std::make_unique<SelfT> (std::forward<Args> (args)...);
instance = cookie.get ();
return cookie;
}
static SelfT&
get (void)
{
return *instance;
}
};
};
template <typename SelfT>
SelfT*
util::singleton<SelfT>::instance;
#endif

14
test/singleton.cpp Normal file
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#include "singleton.hpp"
#include "tap.hpp"
int main ()
{
util::TAP::logger tap;
auto obj = util::singleton<int>::instantiate (42);
tap.expect_eq (util::singleton<int>::get (), 42, "singleton stores value");
return tap.status ();
}