Extract header qtclasshelpermacros.h
Move the class helper macros from qglobal.h and Q_DECLARE_SHARED from qtypeinfo.h there. Task-number: QTBUG-99313 Change-Id: I8c8b6241a76916176a48c09fbaf4effc87683770 Reviewed-by: Edward Welbourne <edward.welbourne@qt.io> Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
This commit is contained in:
Sona Kurazyan
parent
23ecaf897f
commit
c201c5aedf
@ -74,6 +74,7 @@ qt_internal_add_module(Core
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global/qrandom.cpp global/qrandom.h global/qrandom_p.h
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global/qsysinfo.h
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global/qsystemdetection.h
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global/qtclasshelpermacros.h
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global/qtconfigmacros.h
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global/qtdeprecationmarkers.h
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global/qtrace_p.h
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@ -511,63 +511,6 @@ using namespace Qt::StringLiterals;
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(bitmask).
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*/
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/*!
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\macro Q_DISABLE_COPY(Class)
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\relates QObject
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Disables the use of copy constructors and assignment operators
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for the given \a Class.
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Instances of subclasses of QObject should not be thought of as
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values that can be copied or assigned, but as unique identities.
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This means that when you create your own subclass of QObject
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(director or indirect), you should \e not give it a copy constructor
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or an assignment operator. However, it may not enough to simply
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omit them from your class, because, if you mistakenly write some code
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that requires a copy constructor or an assignment operator (it's easy
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to do), your compiler will thoughtfully create it for you. You must
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do more.
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The curious user will have seen that the Qt classes derived
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from QObject typically include this macro in a private section:
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\snippet code/src_corelib_global_qglobal.cpp 43
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It declares a copy constructor and an assignment operator in the
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private section, so that if you use them by mistake, the compiler
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will report an error.
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\snippet code/src_corelib_global_qglobal.cpp 44
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But even this might not catch absolutely every case. You might be
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tempted to do something like this:
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\snippet code/src_corelib_global_qglobal.cpp 45
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First of all, don't do that. Most compilers will generate code that
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uses the copy constructor, so the privacy violation error will be
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reported, but your C++ compiler is not required to generate code for
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this statement in a specific way. It could generate code using
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\e{neither} the copy constructor \e{nor} the assignment operator we
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made private. In that case, no error would be reported, but your
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application would probably crash when you called a member function
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of \c{w}.
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\sa Q_DISABLE_COPY_MOVE
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*/
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/*!
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\macro Q_DISABLE_COPY_MOVE(Class)
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\relates QObject
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A convenience macro that disables the use of copy constructors, assignment
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operators, move constructors and move assignment operators for the given
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\a Class.
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\sa Q_DISABLE_COPY
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\since 5.13
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*/
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/*!
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\macro Q_DECLARE_FLAGS(Flags, Enum)
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\relates QFlags
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@ -46,6 +46,7 @@ inline void qt_noop(void) {}
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#include <QtCore/qassert.h>
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#include <QtCore/qtypes.h>
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#include <QtCore/qtclasshelpermacros.h>
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/*
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Avoid "unused parameter" warnings
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@ -55,65 +56,6 @@ inline void qt_noop(void) {}
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#ifndef __ASSEMBLER__
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QT_BEGIN_NAMESPACE
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/*
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Some classes do not permit copies to be made of an object. These
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classes contains a private copy constructor and assignment
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operator to disable copying (the compiler gives an error message).
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*/
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#define Q_DISABLE_COPY(Class) \
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Class(const Class &) = delete;\
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Class &operator=(const Class &) = delete;
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#define Q_DISABLE_COPY_MOVE(Class) \
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Q_DISABLE_COPY(Class) \
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Class(Class &&) = delete; \
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Class &operator=(Class &&) = delete;
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/*
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Implementing a move assignment operator using an established
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technique (move-and-swap, pure swap) is just boilerplate.
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Here's a couple of *private* macros for convenience.
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To know which one to use:
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* if you don't have a move constructor (*) => use pure swap;
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* if you have a move constructor, then
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* if your class holds just memory (no file handles, no user-defined
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datatypes, etc.) => use pure swap;
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* use move and swap.
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The preference should always go for the move-and-swap one, as it
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will deterministically destroy the data previously held in *this,
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and not "dump" it in the moved-from object (which may then be alive
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for longer).
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The requirement for either macro is the presence of a member swap(),
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which any value class that defines its own special member functions
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should have anyhow.
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(*) Many value classes in Qt do not have move constructors; mostly,
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the implicitly shared classes using QSharedDataPointer and friends.
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The reason is mostly historical: those classes require either an
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out-of-line move constructor, which we could not provide before we
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made C++11 mandatory (and that we don't like anyhow), or
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an out-of-line dtor for the Q(E)DSP<Private> member (cf. QPixmap).
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If you can however add a move constructor to a class lacking it,
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consider doing so, then reevaluate which macro to choose.
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*/
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#define QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(Class) \
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Class &operator=(Class &&other) noexcept { \
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Class moved(std::move(other)); \
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swap(moved); \
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return *this; \
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}
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#define QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(Class) \
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Class &operator=(Class &&other) noexcept { \
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swap(other); \
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return *this; \
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}
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/*
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No, this is not an evil backdoor. QT_BUILD_INTERNAL just exports more symbols
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for Qt's internal unit tests. If you want slower loading times and more
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@ -244,26 +186,6 @@ typedef void (*QFunctionPointer)();
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# define Q_UNIMPLEMENTED() qWarning("Unimplemented code.")
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#endif
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/*
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Compilers which follow outdated template instantiation rules
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require a class to have a comparison operator to exist when
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a QList of this type is instantiated. It's not actually
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used in the list, though. Hence the dummy implementation.
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Just in case other code relies on it we better trigger a warning
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mandating a real implementation.
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*/
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#ifdef Q_FULL_TEMPLATE_INSTANTIATION
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# define Q_DUMMY_COMPARISON_OPERATOR(C) \
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bool operator==(const C&) const { \
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qWarning(#C"::operator==(const "#C"&) was called"); \
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return false; \
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}
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#else
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# define Q_DUMMY_COMPARISON_OPERATOR(C)
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#endif
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QT_WARNING_PUSH
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// warning: noexcept-expression evaluates to 'false' because of a call to 'void swap(..., ...)'
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QT_WARNING_DISABLE_GCC("-Wnoexcept")
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@ -328,33 +250,8 @@ constexpr std::underlying_type_t<Enum> qToUnderlying(Enum e) noexcept
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return static_cast<std::underlying_type_t<Enum>>(e);
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}
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template <typename T> inline T *qGetPtrHelper(T *ptr) noexcept { return ptr; }
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template <typename Ptr> inline auto qGetPtrHelper(Ptr &ptr) noexcept -> decltype(ptr.get())
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{ static_assert(noexcept(ptr.get()), "Smart d pointers for Q_DECLARE_PRIVATE must have noexcept get()"); return ptr.get(); }
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// The body must be a statement:
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#define Q_CAST_IGNORE_ALIGN(body) QT_WARNING_PUSH QT_WARNING_DISABLE_GCC("-Wcast-align") body QT_WARNING_POP
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#define Q_DECLARE_PRIVATE(Class) \
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inline Class##Private* d_func() noexcept \
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{ Q_CAST_IGNORE_ALIGN(return reinterpret_cast<Class##Private *>(qGetPtrHelper(d_ptr));) } \
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inline const Class##Private* d_func() const noexcept \
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{ Q_CAST_IGNORE_ALIGN(return reinterpret_cast<const Class##Private *>(qGetPtrHelper(d_ptr));) } \
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friend class Class##Private;
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#define Q_DECLARE_PRIVATE_D(Dptr, Class) \
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inline Class##Private* d_func() noexcept \
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{ Q_CAST_IGNORE_ALIGN(return reinterpret_cast<Class##Private *>(qGetPtrHelper(Dptr));) } \
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inline const Class##Private* d_func() const noexcept \
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{ Q_CAST_IGNORE_ALIGN(return reinterpret_cast<const Class##Private *>(qGetPtrHelper(Dptr));) } \
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friend class Class##Private;
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#define Q_DECLARE_PUBLIC(Class) \
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inline Class* q_func() noexcept { return static_cast<Class *>(q_ptr); } \
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inline const Class* q_func() const noexcept { return static_cast<const Class *>(q_ptr); } \
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friend class Class;
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#define Q_D(Class) Class##Private * const d = d_func()
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#define Q_Q(Class) Class * const q = q_func()
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#define QT_MODULE(x)
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144
src/corelib/global/qtclasshelpermacros.h
Normal file
144
src/corelib/global/qtclasshelpermacros.h
Normal file
@ -0,0 +1,144 @@
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// Copyright (C) 2022 The Qt Company Ltd.
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// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
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#ifndef QTCLASSHELPERMACROS_H
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#define QTCLASSHELPERMACROS_H
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#include <QtCore/qtconfigmacros.h>
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#if 0
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#pragma qt_class(QtClassHelperMacros)
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#pragma qt_sync_stop_processing
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#endif
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QT_BEGIN_NAMESPACE
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#if defined(__cplusplus)
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/*
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Some classes do not permit copies to be made of an object. These
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classes contains a private copy constructor and assignment
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operator to disable copying (the compiler gives an error message).
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*/
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#define Q_DISABLE_COPY(Class) \
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Class(const Class &) = delete;\
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Class &operator=(const Class &) = delete;
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#define Q_DISABLE_COPY_MOVE(Class) \
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Q_DISABLE_COPY(Class) \
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Class(Class &&) = delete; \
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Class &operator=(Class &&) = delete;
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/*
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Implementing a move assignment operator using an established
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technique (move-and-swap, pure swap) is just boilerplate.
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Here's a couple of *private* macros for convenience.
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To know which one to use:
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* if you don't have a move constructor (*) => use pure swap;
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* if you have a move constructor, then
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* if your class holds just memory (no file handles, no user-defined
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datatypes, etc.) => use pure swap;
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* use move and swap.
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|
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The preference should always go for the move-and-swap one, as it
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will deterministically destroy the data previously held in *this,
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and not "dump" it in the moved-from object (which may then be alive
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for longer).
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The requirement for either macro is the presence of a member swap(),
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which any value class that defines its own special member functions
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should have anyhow.
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(*) Many value classes in Qt do not have move constructors; mostly,
|
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the implicitly shared classes using QSharedDataPointer and friends.
|
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The reason is mostly historical: those classes require either an
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out-of-line move constructor, which we could not provide before we
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made C++11 mandatory (and that we don't like anyhow), or
|
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an out-of-line dtor for the Q(E)DSP<Private> member (cf. QPixmap).
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If you can however add a move constructor to a class lacking it,
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consider doing so, then reevaluate which macro to choose.
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*/
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#define QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(Class) \
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Class &operator=(Class &&other) noexcept { \
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Class moved(std::move(other)); \
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swap(moved); \
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return *this; \
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}
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#define QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(Class) \
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Class &operator=(Class &&other) noexcept { \
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swap(other); \
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return *this; \
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}
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template <typename T> inline T *qGetPtrHelper(T *ptr) noexcept { return ptr; }
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template <typename Ptr> inline auto qGetPtrHelper(Ptr &ptr) noexcept -> decltype(ptr.get())
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{ static_assert(noexcept(ptr.get()), "Smart d pointers for Q_DECLARE_PRIVATE must have noexcept get()"); return ptr.get(); }
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#define Q_DECLARE_PRIVATE(Class) \
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inline Class##Private* d_func() noexcept \
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{ Q_CAST_IGNORE_ALIGN(return reinterpret_cast<Class##Private *>(qGetPtrHelper(d_ptr));) } \
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inline const Class##Private* d_func() const noexcept \
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{ Q_CAST_IGNORE_ALIGN(return reinterpret_cast<const Class##Private *>(qGetPtrHelper(d_ptr));) } \
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friend class Class##Private;
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#define Q_DECLARE_PRIVATE_D(Dptr, Class) \
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inline Class##Private* d_func() noexcept \
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{ Q_CAST_IGNORE_ALIGN(return reinterpret_cast<Class##Private *>(qGetPtrHelper(Dptr));) } \
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inline const Class##Private* d_func() const noexcept \
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{ Q_CAST_IGNORE_ALIGN(return reinterpret_cast<const Class##Private *>(qGetPtrHelper(Dptr));) } \
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friend class Class##Private;
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#define Q_DECLARE_PUBLIC(Class) \
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inline Class* q_func() noexcept { return static_cast<Class *>(q_ptr); } \
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inline const Class* q_func() const noexcept { return static_cast<const Class *>(q_ptr); } \
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friend class Class;
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#define Q_D(Class) Class##Private * const d = d_func()
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#define Q_Q(Class) Class * const q = q_func()
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/*
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Compilers which follow outdated template instantiation rules
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require a class to have a comparison operator to exist when
|
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a QList of this type is instantiated. It's not actually
|
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used in the list, though. Hence the dummy implementation.
|
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Just in case other code relies on it we better trigger a warning
|
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mandating a real implementation.
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*/
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#ifdef Q_FULL_TEMPLATE_INSTANTIATION
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# define Q_DUMMY_COMPARISON_OPERATOR(C) \
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bool operator==(const C&) const { \
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qWarning(#C"::operator==(const "#C"&) was called"); \
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return false; \
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}
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#else
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# define Q_DUMMY_COMPARISON_OPERATOR(C)
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#endif
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/*
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Specialize a shared type with:
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Q_DECLARE_SHARED(type)
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where 'type' is the name of the type to specialize. NOTE: shared
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types must define a member-swap, and be defined in the same
|
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namespace as Qt for this to work.
|
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*/
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#define Q_DECLARE_SHARED_IMPL(TYPE, FLAGS) \
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Q_DECLARE_TYPEINFO(TYPE, FLAGS); \
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inline void swap(TYPE &value1, TYPE &value2) \
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noexcept(noexcept(value1.swap(value2))) \
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{ value1.swap(value2); }
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#define Q_DECLARE_SHARED(TYPE) Q_DECLARE_SHARED_IMPL(TYPE, Q_RELOCATABLE_TYPE)
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#endif // __cplusplus
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QT_END_NAMESPACE
|
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#endif // QTCLASSHELPERMACROS_H
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59
src/corelib/global/qtclasshelpermacros.qdoc
Normal file
59
src/corelib/global/qtclasshelpermacros.qdoc
Normal file
@ -0,0 +1,59 @@
|
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// Copyright (C) 2022 The Qt Company Ltd.
|
||||
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
|
||||
|
||||
/*!
|
||||
\macro Q_DISABLE_COPY(Class)
|
||||
\relates QtClassHelperMacros
|
||||
|
||||
Disables the use of copy constructors and assignment operators
|
||||
for the given \a Class.
|
||||
|
||||
Instances of subclasses of QObject should not be thought of as
|
||||
values that can be copied or assigned, but as unique identities.
|
||||
This means that when you create your own subclass of QObject
|
||||
(director or indirect), you should \e not give it a copy constructor
|
||||
or an assignment operator. However, it may not enough to simply
|
||||
omit them from your class, because, if you mistakenly write some code
|
||||
that requires a copy constructor or an assignment operator (it's easy
|
||||
to do), your compiler will thoughtfully create it for you. You must
|
||||
do more.
|
||||
|
||||
The curious user will have seen that the Qt classes derived
|
||||
from QObject typically include this macro in a private section:
|
||||
|
||||
\snippet code/src_corelib_global_qglobal.cpp 43
|
||||
|
||||
It declares a copy constructor and an assignment operator in the
|
||||
private section, so that if you use them by mistake, the compiler
|
||||
will report an error.
|
||||
|
||||
\snippet code/src_corelib_global_qglobal.cpp 44
|
||||
|
||||
But even this might not catch absolutely every case. You might be
|
||||
tempted to do something like this:
|
||||
|
||||
\snippet code/src_corelib_global_qglobal.cpp 45
|
||||
|
||||
First of all, don't do that. Most compilers will generate code that
|
||||
uses the copy constructor, so the privacy violation error will be
|
||||
reported, but your C++ compiler is not required to generate code for
|
||||
this statement in a specific way. It could generate code using
|
||||
\e{neither} the copy constructor \e{nor} the assignment operator we
|
||||
made private. In that case, no error would be reported, but your
|
||||
application would probably crash when you called a member function
|
||||
of \c{w}.
|
||||
|
||||
\sa Q_DISABLE_COPY_MOVE
|
||||
*/
|
||||
|
||||
/*!
|
||||
\macro Q_DISABLE_COPY_MOVE(Class)
|
||||
\relates QtClassHelperMacros
|
||||
|
||||
A convenience macro that disables the use of copy constructors, assignment
|
||||
operators, move constructors and move assignment operators for the given
|
||||
\a Class.
|
||||
|
||||
\sa Q_DISABLE_COPY
|
||||
\since 5.13
|
||||
*/
|
||||
@ -143,23 +143,6 @@ template<typename T> class QFlags;
|
||||
template<typename T>
|
||||
Q_DECLARE_TYPEINFO_BODY(QFlags<T>, Q_PRIMITIVE_TYPE);
|
||||
|
||||
/*
|
||||
Specialize a shared type with:
|
||||
|
||||
Q_DECLARE_SHARED(type)
|
||||
|
||||
where 'type' is the name of the type to specialize. NOTE: shared
|
||||
types must define a member-swap, and be defined in the same
|
||||
namespace as Qt for this to work.
|
||||
*/
|
||||
|
||||
#define Q_DECLARE_SHARED_IMPL(TYPE, FLAGS) \
|
||||
Q_DECLARE_TYPEINFO(TYPE, FLAGS); \
|
||||
inline void swap(TYPE &value1, TYPE &value2) \
|
||||
noexcept(noexcept(value1.swap(value2))) \
|
||||
{ value1.swap(value2); }
|
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#define Q_DECLARE_SHARED(TYPE) Q_DECLARE_SHARED_IMPL(TYPE, Q_RELOCATABLE_TYPE)
|
||||
|
||||
namespace QTypeTraits
|
||||
{
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user