diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/corelib/tools/qscopeguard.h | 37 | ||||
-rw-r--r-- | src/corelib/tools/qscopeguard.qdoc | 41 |
2 files changed, 55 insertions, 23 deletions
diff --git a/src/corelib/tools/qscopeguard.h b/src/corelib/tools/qscopeguard.h index 40d2747b1d..4d2e715df1 100644 --- a/src/corelib/tools/qscopeguard.h +++ b/src/corelib/tools/qscopeguard.h @@ -1,6 +1,7 @@ /**************************************************************************** ** ** Copyright (C) 2018 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Sérgio Martins <sergio.martins@kdab.com> +** Copyright (C) 2019 The Qt Company Ltd. ** Contact: https://www.qt.io/licensing/ ** ** This file is part of the QtCore module of the Qt Toolkit. @@ -45,10 +46,6 @@ QT_BEGIN_NAMESPACE - -template <typename F> class QScopeGuard; -template <typename F> QScopeGuard<F> qScopeGuard(F f); - template <typename F> class #if __has_cpp_attribute(nodiscard) @@ -59,13 +56,23 @@ Q_REQUIRED_RESULT QScopeGuard { public: + explicit QScopeGuard(F &&f) noexcept + : m_func(std::move(f)) + { + } + + explicit QScopeGuard(const F &f) noexcept + : m_func(f) + { + } + QScopeGuard(QScopeGuard &&other) noexcept : m_func(std::move(other.m_func)) , m_invoke(qExchange(other.m_invoke, false)) { } - ~QScopeGuard() + ~QScopeGuard() noexcept { if (m_invoke) m_func(); @@ -77,28 +84,34 @@ public: } private: - explicit QScopeGuard(F &&f) noexcept - : m_func(std::move(f)) - { - } - Q_DISABLE_COPY(QScopeGuard) F m_func; bool m_invoke = true; - friend QScopeGuard qScopeGuard<F>(F); }; +#ifdef __cpp_deduction_guides +template <typename F> QScopeGuard(F(&)()) -> QScopeGuard<F(*)()>; +#endif template <typename F> #if __has_cpp_attribute(nodiscard) Q_REQUIRED_RESULT #endif -QScopeGuard<F> qScopeGuard(F f) +QScopeGuard<F> qScopeGuard(F &&f) { return QScopeGuard<F>(std::move(f)); } +template <typename F> +#if __has_cpp_attribute(nodiscard) +Q_REQUIRED_RESULT +#endif +QScopeGuard<F> qScopeGuard(const F &f) +{ + return QScopeGuard<F>(f); +} + QT_END_NAMESPACE #endif // QSCOPEGUARD_H diff --git a/src/corelib/tools/qscopeguard.qdoc b/src/corelib/tools/qscopeguard.qdoc index 6b3c942e84..572934d890 100644 --- a/src/corelib/tools/qscopeguard.qdoc +++ b/src/corelib/tools/qscopeguard.qdoc @@ -1,6 +1,7 @@ /**************************************************************************** ** ** Copyright (C) 2018 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Sérgio Martins <sergio.martins@kdab.com> +** Copyright (C) 2019 The Qt Company Ltd. ** Contact: https://www.qt.io/licensing/ ** ** This file is part of the documentation of the Qt Toolkit. @@ -35,6 +36,30 @@ QT_BEGIN_NAMESPACE \inmodule QtCore \brief Provides a scope guard for calling a function at the end of a scope. + + QScopeGuard<F> is a class of which the sole purpose is to run the function + \a f in its destructor. This is useful for guaranteeing + your cleanup code is executed, whether the function is exited normally, + exited early by a return statement, or exited by an exception. + + \note Exceptions are not supported. The callable shouldn't throw when + executed, copied or moved. + + \sa QScopedValueRollback +*/ + +/*! + \fn template <typename F> QScopeGuard<F>::QScopeGuard(F &&f) + \fn template <typename F> QScopeGuard<F>::QScopeGuard(const F &f) + + Create a scope guard that will execute \a f at the end of the scope. + + If \e F is a lambda, its type cannot be written. In that case you need to + either rely on class template argument deduction (C++17 feature) and leave + the template parameter out completely or use the helper function + qScopeGuard() instead of this constructor. + + \since 5.15 */ /*! \fn template <typename F> void QScopeGuard<F>::dismiss() @@ -51,23 +76,17 @@ QT_BEGIN_NAMESPACE of the scope. \ingroup misc - QScopeGuard<F> is a class of which the sole purpose is to run the function - \a f in its destructor. This is useful for guaranteeing - your cleanup code is executed, whether the function is exited normally, - exited early by a return statement, or exited by an exception. + Create a scope guard that will execute \a f at the end of the scope. - If \e F is a lambda then you cannot instantiate the template directly, - therefore the qScopeGuard() helper is provided and QScopeGuard<F> is made a - private implementation detail. + This helper function is provided so that you can easily construct a + QScopeGuard without having to name the template parameter for the type of + the callable. If \e F is a lambda then you cannot write its type and relying + on this helper or class template argument deduction is necessary. Example usage is as follows: \snippet code/src_corelib_tools_qscopeguard.cpp 0 - \note Exceptions are not supported. The callable shouldn't throw when - executed, copied or moved. - - \sa QScopedValueRollback */ QT_END_NAMESPACE |