diff options
Diffstat (limited to 'src/corelib/tools/qshareddata.cpp')
| -rw-r--r-- | src/corelib/tools/qshareddata.cpp | 663 |
1 files changed, 329 insertions, 334 deletions
diff --git a/src/corelib/tools/qshareddata.cpp b/src/corelib/tools/qshareddata.cpp index 9f49898..70290d8 100644 --- a/src/corelib/tools/qshareddata.cpp +++ b/src/corelib/tools/qshareddata.cpp @@ -44,245 +44,242 @@ QT_BEGIN_NAMESPACE /*! - \class QSharedData - \brief The QSharedData class is a base class for shared data objects. - \reentrant - \ingroup misc + \class QSharedData + \brief The QSharedData class is a base class for shared data objects. + \reentrant - QSharedData is designed to be used with QSharedDataPointer or - QExplicitlySharedDataPointer to implement custom \l{implicitly - shared} or explicitly shared classes. QSharedData provides - \l{thread-safe} reference counting. + QSharedData is designed to be used with QSharedDataPointer or + QExplicitlySharedDataPointer to implement custom \l{implicitly + shared} or explicitly shared classes. QSharedData provides + \l{thread-safe} reference counting. - See QSharedDataPointer and QExplicitlySharedDataPointer for details. + See QSharedDataPointer and QExplicitlySharedDataPointer for details. */ /*! \fn QSharedData::QSharedData() - Constructs a QSharedData object with a reference count of 0. + Constructs a QSharedData object with a reference count of 0. */ /*! \fn QSharedData::QSharedData(const QSharedData& other) - Constructs a QSharedData object with reference count 0. - \a other is ignored. + Constructs a QSharedData object with reference count 0. + \a other is ignored. */ /*! - \class QSharedDataPointer - \brief The QSharedDataPointer class represents a pointer to an implicitly shared object. - \since 4.0 - \reentrant - \ingroup misc - \mainclass + \class QSharedDataPointer + \brief The QSharedDataPointer class represents a pointer to an implicitly shared object. + \since 4.0 + \reentrant - QSharedDataPointer\<T\> makes writing your own \l {implicitly - shared} classes easy. QSharedDataPointer implements \l {thread-safe} - reference counting, ensuring that adding QSharedDataPointers to your - \l {reentrant} classes won't make them non-reentrant. + QSharedDataPointer\<T\> makes writing your own \l {implicitly + shared} classes easy. QSharedDataPointer implements \l {thread-safe} + reference counting, ensuring that adding QSharedDataPointers to your + \l {reentrant} classes won't make them non-reentrant. - \l {Implicit sharing} is used by many Qt classes to combine the - speed and memory efficiency of pointers with the ease of use of - classes. See the \l{Shared Classes} page for more information. + \l {Implicit sharing} is used by many Qt classes to combine the + speed and memory efficiency of pointers with the ease of use of + classes. See the \l{Shared Classes} page for more information. - \target Employee example - Suppose you want to make an \c Employee class implicitly shared. The - procedure is: + \target Employee example + Suppose you want to make an \c Employee class implicitly shared. The + procedure is: - \list + \list - \o Define the class \c Employee to have a single data member of + \o Define the class \c Employee to have a single data member of type \c {QSharedDataPointer<EmployeeData>}. - \o Define the \c EmployeeData class derived from \l QSharedData to + \o Define the \c EmployeeData class derived from \l QSharedData to contain all the data members you would normally have put in the \c Employee class. - \endlist - - To show this in practice, we review the source code for the - implicitly shared \c Employee class. In the header file we define the - two classes \c Employee and \c EmployeeData. - - \snippet doc/src/snippets/sharedemployee/employee.h 0 - - In class \c Employee, note the single data member, a \e {d pointer} - of type \c {QSharedDataPointer<EmployeeData>}. All accesses of - employee data must go through the \e {d pointer's} \c - {operator->()}. For write accesses, \c {operator->()} will - automatically call detach(), which creates a copy of the shared data - object if the shared data object's reference count is greater than - 1. This ensures that writes to one \c Employee object don't affect - any other \c Employee objects that share the same \c EmployeeData - object. - - Class \c EmployeeData inherits QSharedData, which provides the - \e{behind the scenes} reference counter. \c EmployeeData has a default - constructor, a copy constructor, and a destructor. Normally, trivial - implementations of these are all that is needed in the \e {data} - class for an implicitly shared class. - - Implementing the two constructors for class \c Employee is also - straightforward. Both create a new instance of \c EmployeeData - and assign it to the \e{d pointer} . - - \snippet doc/src/snippets/sharedemployee/employee.h 1 - \codeline - \snippet doc/src/snippets/sharedemployee/employee.h 2 - - Note that class \c Employee also has a trivial copy constructor - defined, which is not strictly required in this case. - - \snippet doc/src/snippets/sharedemployee/employee.h 7 - - The copy constructor is not strictly required here, because class \c - EmployeeData is included in the same file as class \c Employee - (\c{employee.h}). However, including the private subclass of - QSharedData in the same file as the public class containing the - QSharedDataPointer is not typical. Normally, the idea is to hide the - private subclass of QSharedData from the user by putting it in a - separate file which would not be included in the public file. In - this case, we would normally put class \c EmployeeData in a separate - file, which would \e{not} be included in \c{employee.h}. Instead, we - would just predeclare the private subclass \c EmployeeData in \c - {employee.h} this way: - - \code - class EmployeeData; - \endcode - - If we had done it that way here, the copy constructor shown would be - required. Since the copy constructor is trivial, you might as well - just always include it. - - Behind the scenes, QSharedDataPointer automatically increments the - reference count whenever an \c Employee object is copied, assigned, - or passed as a parameter. It decrements the reference count whenever - an \c Employee object is deleted or goes out of scope. The shared - \c EmployeeData object is deleted automatically if and when the - reference count reaches 0. - - In a non-const member function of \c Employee, whenever the \e {d - pointer} is dereferenced, QSharedDataPointer automatically calls - detach() to ensure that the function operates on its own copy of the - data. - - \snippet doc/src/snippets/sharedemployee/employee.h 3 - \codeline - \snippet doc/src/snippets/sharedemployee/employee.h 4 - - Note that if detach() is called more than once in a member function - due to multiple dereferences of the \e {d pointer}, detach() will - only create a copy of the shared data the first time it is called, - if at all, because on the second and subsequent calls of detach(), - the reference count will be 1 again. - - But note that in the second \c Employee constructor, which takes an - employee ID and a name, both setId() and setName() are called, but - they don't cause \e{copy on write}, because the reference count for - the newly constructed \c EmployeeData object has just been set to 1. - - In \c Employee's \e const member functions, dereferencing the \e {d - pointer} does \e not cause detach() to be called. - - \snippet doc/src/snippets/sharedemployee/employee.h 5 - \codeline - \snippet doc/src/snippets/sharedemployee/employee.h 6 - - Notice that there is no need to implement a copy constructor or an - assignment operator for the \c Employee class, because the copy - constructor and assignment operator provided by the C++ compiler - will do the \e{member by member} shallow copy required. The only - member to copy is the \e {d pointer}, which is a QSharedDataPointer, - whose \c {operator=()} just increments the reference count of the - shared \c EmployeeData object. - - \target Implicit vs Explicit Sharing - \section1 Implicit vs Explicit Sharing - - Implicit sharing might not be right for the \c Employee class. - Consider a simple example that creates two instances of the - implicitly shared \c Employee class. - - \snippet doc/src/snippets/sharedemployee/main.cpp 0 - - After the second employee e2 is created and e1 is assigned to it, - both \c e1 and \c e2 refer to Albrecht Durer, employee 1001. Both \c - Employee objects point to the same instance of \c EmployeeData, - which has reference count 2. Then \c {e1.setName("Hans Holbein")} is - called to change the employee name, but because the reference count - is greater than 1, a \e{copy on write} is performed before the name - is changed. Now \c e1 and \c e2 point to different \c EmployeeData - objects. They have different names, but both have ID 1001, which is - probably not what you want. You can, of course, just continue with - \c {e1.setId(1002)}, if you really mean to create a second, unique - employee, but if you only want to change the employee's name - everywhere, consider using \l {QExplicitlySharedDataPointer} - {explicit sharing} in the \c Employee class instead of implicit - sharing. - - If you declare the \e {d pointer} in the \c Employee class to be - \c {QExplicitlySharedDataPointer<EmployeeData>}, then explicit - sharing is used and \e{copy on write} operations are not performed - automatically (i.e. detach() is not called in non-const - functions). In that case, after \c {e1.setName("Hans Holbein")}, the - employee's name has been changed, but both e1 and e2 still refer to - the same instance of \c EmployeeData, so there is only one employee - with ID 1001. - - In the member function documentation, \e{d pointer} always refers - to the internal pointer to the shared data object. - - \sa QSharedData, QExplicitlySharedDataPointer + \endlist + + To show this in practice, we review the source code for the + implicitly shared \c Employee class. In the header file we define the + two classes \c Employee and \c EmployeeData. + + \snippet doc/src/snippets/sharedemployee/employee.h 0 + + In class \c Employee, note the single data member, a \e {d pointer} + of type \c {QSharedDataPointer<EmployeeData>}. All accesses of + employee data must go through the \e {d pointer's} \c + {operator->()}. For write accesses, \c {operator->()} will + automatically call detach(), which creates a copy of the shared data + object if the shared data object's reference count is greater than + 1. This ensures that writes to one \c Employee object don't affect + any other \c Employee objects that share the same \c EmployeeData + object. + + Class \c EmployeeData inherits QSharedData, which provides the + \e{behind the scenes} reference counter. \c EmployeeData has a default + constructor, a copy constructor, and a destructor. Normally, trivial + implementations of these are all that is needed in the \e {data} + class for an implicitly shared class. + + Implementing the two constructors for class \c Employee is also + straightforward. Both create a new instance of \c EmployeeData + and assign it to the \e{d pointer} . + + \snippet doc/src/snippets/sharedemployee/employee.h 1 + \codeline + \snippet doc/src/snippets/sharedemployee/employee.h 2 + + Note that class \c Employee also has a trivial copy constructor + defined, which is not strictly required in this case. + + \snippet doc/src/snippets/sharedemployee/employee.h 7 + + The copy constructor is not strictly required here, because class \c + EmployeeData is included in the same file as class \c Employee + (\c{employee.h}). However, including the private subclass of + QSharedData in the same file as the public class containing the + QSharedDataPointer is not typical. Normally, the idea is to hide the + private subclass of QSharedData from the user by putting it in a + separate file which would not be included in the public file. In + this case, we would normally put class \c EmployeeData in a separate + file, which would \e{not} be included in \c{employee.h}. Instead, we + would just predeclare the private subclass \c EmployeeData in \c + {employee.h} this way: + + \code + class EmployeeData; + \endcode + + If we had done it that way here, the copy constructor shown would be + required. Since the copy constructor is trivial, you might as well + just always include it. + + Behind the scenes, QSharedDataPointer automatically increments the + reference count whenever an \c Employee object is copied, assigned, + or passed as a parameter. It decrements the reference count whenever + an \c Employee object is deleted or goes out of scope. The shared + \c EmployeeData object is deleted automatically if and when the + reference count reaches 0. + + In a non-const member function of \c Employee, whenever the \e {d + pointer} is dereferenced, QSharedDataPointer automatically calls + detach() to ensure that the function operates on its own copy of the + data. + + \snippet doc/src/snippets/sharedemployee/employee.h 3 + \codeline + \snippet doc/src/snippets/sharedemployee/employee.h 4 + + Note that if detach() is called more than once in a member function + due to multiple dereferences of the \e {d pointer}, detach() will + only create a copy of the shared data the first time it is called, + if at all, because on the second and subsequent calls of detach(), + the reference count will be 1 again. + + But note that in the second \c Employee constructor, which takes an + employee ID and a name, both setId() and setName() are called, but + they don't cause \e{copy on write}, because the reference count for + the newly constructed \c EmployeeData object has just been set to 1. + + In \c Employee's \e const member functions, dereferencing the \e {d + pointer} does \e not cause detach() to be called. + + \snippet doc/src/snippets/sharedemployee/employee.h 5 + \codeline + \snippet doc/src/snippets/sharedemployee/employee.h 6 + + Notice that there is no need to implement a copy constructor or an + assignment operator for the \c Employee class, because the copy + constructor and assignment operator provided by the C++ compiler + will do the \e{member by member} shallow copy required. The only + member to copy is the \e {d pointer}, which is a QSharedDataPointer, + whose \c {operator=()} just increments the reference count of the + shared \c EmployeeData object. + + \target Implicit vs Explicit Sharing + \section1 Implicit vs Explicit Sharing + + Implicit sharing might not be right for the \c Employee class. + Consider a simple example that creates two instances of the + implicitly shared \c Employee class. + + \snippet doc/src/snippets/sharedemployee/main.cpp 0 + + After the second employee e2 is created and e1 is assigned to it, + both \c e1 and \c e2 refer to Albrecht Durer, employee 1001. Both \c + Employee objects point to the same instance of \c EmployeeData, + which has reference count 2. Then \c {e1.setName("Hans Holbein")} is + called to change the employee name, but because the reference count + is greater than 1, a \e{copy on write} is performed before the name + is changed. Now \c e1 and \c e2 point to different \c EmployeeData + objects. They have different names, but both have ID 1001, which is + probably not what you want. You can, of course, just continue with + \c {e1.setId(1002)}, if you really mean to create a second, unique + employee, but if you only want to change the employee's name + everywhere, consider using \l {QExplicitlySharedDataPointer} + {explicit sharing} in the \c Employee class instead of implicit + sharing. + + If you declare the \e {d pointer} in the \c Employee class to be + \c {QExplicitlySharedDataPointer<EmployeeData>}, then explicit + sharing is used and \e{copy on write} operations are not performed + automatically (i.e. detach() is not called in non-const + functions). In that case, after \c {e1.setName("Hans Holbein")}, the + employee's name has been changed, but both e1 and e2 still refer to + the same instance of \c EmployeeData, so there is only one employee + with ID 1001. + + In the member function documentation, \e{d pointer} always refers + to the internal pointer to the shared data object. + + \sa QSharedData, QExplicitlySharedDataPointer */ /*! \fn T& QSharedDataPointer::operator*() - Provides access to the shared data object's members. - This function calls detach(). + Provides access to the shared data object's members. + This function calls detach(). */ /*! \fn const T& QSharedDataPointer::operator*() const - Provides const access to the shared data object's members. - This function does \e not call detach(). + Provides const access to the shared data object's members. + This function does \e not call detach(). */ /*! \fn T* QSharedDataPointer::operator->() - Provides access to the shared data object's members. - This function calls detach(). + Provides access to the shared data object's members. + This function calls detach(). */ /*! \fn const T* QSharedDataPointer::operator->() const - Provides const access to the shared data object's members. - This function does \e not call detach(). + Provides const access to the shared data object's members. + This function does \e not call detach(). */ /*! \fn QSharedDataPointer::operator T*() - Returns a pointer to the shared data object. - This function calls detach(). + Returns a pointer to the shared data object. + This function calls detach(). - \sa data(), constData() + \sa data(), constData() */ /*! \fn QSharedDataPointer::operator const T*() const - Returns a pointer to the shared data object. - This function does \e not call detach(). + Returns a pointer to the shared data object. + This function does \e not call detach(). */ /*! \fn T* QSharedDataPointer::data() - Returns a pointer to the shared data object. - This function calls detach(). + Returns a pointer to the shared data object. + This function calls detach(). - \sa constData() + \sa constData() */ /*! \fn const T* QSharedDataPointer::data() const - Returns a pointer to the shared data object. - This function does \e not call detach(). + Returns a pointer to the shared data object. + This function does \e not call detach(). */ /*! \fn const T* QSharedDataPointer::constData() const - Returns a const pointer to the shared data object. - This function does \e not call detach(). + Returns a const pointer to the shared data object. + This function does \e not call detach(). - \sa data() + \sa data() */ /*! \fn void QSharedDataPointer::swap(QSharedDataPointer &other) @@ -291,154 +288,152 @@ QT_BEGIN_NAMESPACE */ /*! \fn bool QSharedDataPointer::operator==(const QSharedDataPointer<T>& other) const - Returns true if \a other and \e this have the same \e{d pointer}. - This function does \e not call detach(). + Returns true if \a other and \e this have the same \e{d pointer}. + This function does \e not call detach(). */ /*! \fn bool QSharedDataPointer::operator!=(const QSharedDataPointer<T>& other) const - Returns true if \a other and \e this do \e not have the same - \e{d pointer}. This function does \e not call detach(). + Returns true if \a other and \e this do \e not have the same + \e{d pointer}. This function does \e not call detach(). */ /*! \fn QSharedDataPointer::QSharedDataPointer() - Constructs a QSharedDataPointer initialized with a null \e{d pointer}. + Constructs a QSharedDataPointer initialized with a null \e{d pointer}. */ /*! \fn QSharedDataPointer::~QSharedDataPointer() - Decrements the reference count of the shared data object. - If the reference count becomes 0, the shared data object - is deleted. \e This is then destroyed. + Decrements the reference count of the shared data object. + If the reference count becomes 0, the shared data object + is deleted. \e This is then destroyed. */ /*! \fn QSharedDataPointer::QSharedDataPointer(T* sharedData) - Constructs a QSharedDataPointer with \e{d pointer} set to - \a sharedData and increments \a{sharedData}'s reference count. + Constructs a QSharedDataPointer with \e{d pointer} set to + \a sharedData and increments \a{sharedData}'s reference count. */ /*! \fn QSharedDataPointer::QSharedDataPointer(const QSharedDataPointer<T>& other) - Sets the \e{d pointer} of \e this to the \e{d pointer} in - \a other and increments the reference count of the shared - data object. + Sets the \e{d pointer} of \e this to the \e{d pointer} in + \a other and increments the reference count of the shared + data object. */ /*! \fn QSharedDataPointer<T>& QSharedDataPointer::operator=(const QSharedDataPointer<T>& other) - Sets the \e{d pointer} of \e this to the \e{d pointer} of - \a other and increments the reference count of the shared - data object. The reference count of the old shared data - object of \e this is decremented. If the reference count - of the old shared data object becomes 0, the old shared - data object is deleted. + Sets the \e{d pointer} of \e this to the \e{d pointer} of + \a other and increments the reference count of the shared + data object. The reference count of the old shared data + object of \e this is decremented. If the reference count + of the old shared data object becomes 0, the old shared + data object is deleted. */ /*! \fn QSharedDataPointer& QSharedDataPointer::operator=(T* sharedData) - Sets the \e{d pointer} og \e this to \a sharedData and increments - \a{sharedData}'s reference count. The reference count of the old - shared data object of \e this is decremented. If the reference - count of the old shared data object becomes 0, the old shared data - object is deleted. + Sets the \e{d pointer} og \e this to \a sharedData and increments + \a{sharedData}'s reference count. The reference count of the old + shared data object of \e this is decremented. If the reference + count of the old shared data object becomes 0, the old shared data + object is deleted. */ /*! \fn bool QSharedDataPointer::operator!() const - Returns true if the \e{d pointer} of \e this is null. + Returns true if the \e{d pointer} of \e this is null. */ /*! \fn void QSharedDataPointer::detach() - If the shared data object's reference count is greater than 1, this - function creates a deep copy of the shared data object and sets the - \e{d pointer} of \e this to the copy. - - This function is called automatically by non-const member - functions of QSharedDataPointer if \e{copy on write} is - required. You don't need to call it yourself. + If the shared data object's reference count is greater than 1, this + function creates a deep copy of the shared data object and sets the + \e{d pointer} of \e this to the copy. + + This function is called automatically by non-const member + functions of QSharedDataPointer if \e{copy on write} is + required. You don't need to call it yourself. */ /*! \fn T *QSharedDataPointer::clone() \since 4.5 - Creates and returns a deep copy of the current data. This function - is called by detach() when the reference count is greater than 1 in - order to create the new copy. This function uses the \e {operator - new} and calls the copy constructor of the type T. + Creates and returns a deep copy of the current data. This function + is called by detach() when the reference count is greater than 1 in + order to create the new copy. This function uses the \e {operator + new} and calls the copy constructor of the type T. - This function is provided so that you may support "virtual copy - constructors" for your own types. In order to so, you should declare - a template-specialization of this function for your own type, like - the example below: + This function is provided so that you may support "virtual copy + constructors" for your own types. In order to so, you should declare + a template-specialization of this function for your own type, like + the example below: - \code + \code template<> EmployeeData *QSharedDataPointer<EmployeeData>::clone() { return d->clone(); } - \endcode + \endcode - In the example above, the template specialization for the clone() - function calls the \e {EmployeeData::clone()} virtual function. A - class derived from EmployeeData could override that function and - return the proper polymorphic type. + In the example above, the template specialization for the clone() + function calls the \e {EmployeeData::clone()} virtual function. A + class derived from EmployeeData could override that function and + return the proper polymorphic type. */ /*! - \class QExplicitlySharedDataPointer - \brief The QExplicitlySharedDataPointer class represents a pointer to an explicitly shared object. - \since 4.4 - \reentrant - \ingroup misc - \mainclass - - QExplicitlySharedDataPointer\<T\> makes writing your own explicitly - shared classes easy. QExplicitlySharedDataPointer implements - \l {thread-safe} reference counting, ensuring that adding - QExplicitlySharedDataPointers to your \l {reentrant} classes won't - make them non-reentrant. - - Except for one big difference, QExplicitlySharedDataPointer is just - like QSharedDataPointer. The big difference is that member functions - of QExplicitlySharedDataPointer \e{do not} do the automatic - \e{copy on write} operation (detach()) that non-const members of - QSharedDataPointer do before allowing the shared data object to be - modified. There is a detach() function available, but if you really - want to detach(), you have to call it yourself. This means that - QExplicitlySharedDataPointers behave like regular C++ pointers, - except that by doing reference counting and not deleting the shared - data object until the reference count is 0, they avoid the dangling - pointer problem. - - It is instructive to compare QExplicitlySharedDataPointer with - QSharedDataPointer by way of an example. Consider the \l {Employee - example} in QSharedDataPointer, modified to use explicit sharing as - explained in the discussion \l {Implicit vs Explicit Sharing}. - - Note that if you use this class but find you are calling detach() a - lot, you probably should be using QSharedDataPointer instead. - - In the member function documentation, \e{d pointer} always refers - to the internal pointer to the shared data object. - - \sa QSharedData, QSharedDataPointer + \class QExplicitlySharedDataPointer + \brief The QExplicitlySharedDataPointer class represents a pointer to an explicitly shared object. + \since 4.4 + \reentrant + + QExplicitlySharedDataPointer\<T\> makes writing your own explicitly + shared classes easy. QExplicitlySharedDataPointer implements + \l {thread-safe} reference counting, ensuring that adding + QExplicitlySharedDataPointers to your \l {reentrant} classes won't + make them non-reentrant. + + Except for one big difference, QExplicitlySharedDataPointer is just + like QSharedDataPointer. The big difference is that member functions + of QExplicitlySharedDataPointer \e{do not} do the automatic + \e{copy on write} operation (detach()) that non-const members of + QSharedDataPointer do before allowing the shared data object to be + modified. There is a detach() function available, but if you really + want to detach(), you have to call it yourself. This means that + QExplicitlySharedDataPointers behave like regular C++ pointers, + except that by doing reference counting and not deleting the shared + data object until the reference count is 0, they avoid the dangling + pointer problem. + + It is instructive to compare QExplicitlySharedDataPointer with + QSharedDataPointer by way of an example. Consider the \l {Employee + example} in QSharedDataPointer, modified to use explicit sharing as + explained in the discussion \l {Implicit vs Explicit Sharing}. + + Note that if you use this class but find you are calling detach() a + lot, you probably should be using QSharedDataPointer instead. + + In the member function documentation, \e{d pointer} always refers + to the internal pointer to the shared data object. + + \sa QSharedData, QSharedDataPointer */ /*! \fn T& QExplicitlySharedDataPointer::operator*() const - Provides access to the shared data object's members. + Provides access to the shared data object's members. */ /*! \fn T* QExplicitlySharedDataPointer::operator->() - Provides access to the shared data object's members. + Provides access to the shared data object's members. */ /*! \fn const T* QExplicitlySharedDataPointer::operator->() const - Provides const access to the shared data object's members. + Provides const access to the shared data object's members. */ /*! \fn T* QExplicitlySharedDataPointer::data() const - Returns a pointer to the shared data object. + Returns a pointer to the shared data object. */ /*! \fn const T* QExplicitlySharedDataPointer::constData() const - Returns a const pointer to the shared data object. + Returns a const pointer to the shared data object. - \sa data() + \sa data() */ /*! \fn void QExplicitlySharedDataPointer::swap(QExplicitlySharedDataPointer &other) @@ -447,114 +442,114 @@ QT_BEGIN_NAMESPACE */ /*! \fn bool QExplicitlySharedDataPointer::operator==(const QExplicitlySharedDataPointer<T>& other) const - Returns true if \a other and \e this have the same \e{d pointer}. + Returns true if \a other and \e this have the same \e{d pointer}. */ /*! \fn bool QExplicitlySharedDataPointer::operator==(const T* ptr) const - Returns true if the \e{d pointer} of \e this is \a ptr. + Returns true if the \e{d pointer} of \e this is \a ptr. */ /*! \fn bool QExplicitlySharedDataPointer::operator!=(const QExplicitlySharedDataPointer<T>& other) const - Returns true if \a other and \e this do \e not have the same - \e{d pointer}. + Returns true if \a other and \e this do \e not have the same + \e{d pointer}. */ /*! \fn bool QExplicitlySharedDataPointer::operator!=(const T* ptr) const - Returns true if the \e{d pointer} of \e this is \e not \a ptr. + Returns true if the \e{d pointer} of \e this is \e not \a ptr. */ /*! \fn QExplicitlySharedDataPointer::QExplicitlySharedDataPointer() - Constructs a QExplicitlySharedDataPointer initialized with a null - \e{d pointer}. + Constructs a QExplicitlySharedDataPointer initialized with a null + \e{d pointer}. */ /*! \fn QExplicitlySharedDataPointer::~QExplicitlySharedDataPointer() - Decrements the reference count of the shared data object. - If the reference count becomes 0, the shared data object - is deleted. \e This is then destroyed. + Decrements the reference count of the shared data object. + If the reference count becomes 0, the shared data object + is deleted. \e This is then destroyed. */ /*! \fn QExplicitlySharedDataPointer::QExplicitlySharedDataPointer(T* sharedData) - Constructs a QExplicitlySharedDataPointer with \e{d pointer} - set to \a sharedData and increments \a{sharedData}'s reference - count. + Constructs a QExplicitlySharedDataPointer with \e{d pointer} + set to \a sharedData and increments \a{sharedData}'s reference + count. */ /*! \fn QExplicitlySharedDataPointer::QExplicitlySharedDataPointer(const QExplicitlySharedDataPointer<T>& other) - This standard copy constructor sets the \e {d pointer} of \e this to - the \e {d pointer} in \a other and increments the reference count of - the shared data object. + This standard copy constructor sets the \e {d pointer} of \e this to + the \e {d pointer} in \a other and increments the reference count of + the shared data object. */ /*! \fn QExplicitlySharedDataPointer::QExplicitlySharedDataPointer(const QExplicitlySharedDataPointer<X>& other) - This copy constructor is different in that it allows \a other to be - a different type of explicitly shared data pointer but one that has - a compatible shared data object. It performs a static cast of the - \e{d pointer} in \a other and sets the \e {d pointer} of \e this to - the converted \e{d pointer}. It increments the reference count of - the shared data object. - */ + This copy constructor is different in that it allows \a other to be + a different type of explicitly shared data pointer but one that has + a compatible shared data object. It performs a static cast of the + \e{d pointer} in \a other and sets the \e {d pointer} of \e this to + the converted \e{d pointer}. It increments the reference count of + the shared data object. +*/ /*! \fn QExplicitlySharedDataPointer<T>& QExplicitlySharedDataPointer::operator=(const QExplicitlySharedDataPointer<T>& other) - Sets the \e{d pointer} of \e this to the \e{d pointer} of - \a other and increments the reference count of the shared - data object. The reference count of the old shared data - object of \e this is decremented. If the reference count - of the old shared data object becomes 0, the old shared - data object is deleted. + Sets the \e{d pointer} of \e this to the \e{d pointer} of + \a other and increments the reference count of the shared + data object. The reference count of the old shared data + object of \e this is decremented. If the reference count + of the old shared data object becomes 0, the old shared + data object is deleted. */ /*! \fn QExplicitlySharedDataPointer& QExplicitlySharedDataPointer::operator=(T* sharedData) - Sets the \e{d pointer} of \e this to \a sharedData and - increments \a{sharedData}'s reference count. The reference - count of the old shared data object of \e this is decremented. - If the reference count of the old shared data object becomes - 0, the old shared data object is deleted. + Sets the \e{d pointer} of \e this to \a sharedData and + increments \a{sharedData}'s reference count. The reference + count of the old shared data object of \e this is decremented. + If the reference count of the old shared data object becomes + 0, the old shared data object is deleted. */ /*! \fn void QExplicitlySharedDataPointer::reset() - Resets \e this to be null. i.e., this function sets the - \e{d pointer} of \e this to 0, but first it decrements - the reference count of the shared data object and deletes - the shared data object if the reference count became 0. + Resets \e this to be null. i.e., this function sets the + \e{d pointer} of \e this to 0, but first it decrements + the reference count of the shared data object and deletes + the shared data object if the reference count became 0. */ /*! \fn QExplicitlySharedDataPointer::operator bool () const - Returns true if the \e{d pointer} of \e this is \e not null. + Returns true if the \e{d pointer} of \e this is \e not null. */ /*! \fn bool QExplicitlySharedDataPointer::operator!() const - Returns true if the \e{d pointer} of \e this is null. + Returns true if the \e{d pointer} of \e this is null. */ /*! \fn void QExplicitlySharedDataPointer::detach() - If the shared data object's reference count is greater than 1, this - function creates a deep copy of the shared data object and sets the - \e{d pointer} of \e this to the copy. + If the shared data object's reference count is greater than 1, this + function creates a deep copy of the shared data object and sets the + \e{d pointer} of \e this to the copy. - Because QExplicitlySharedDataPointer does not do the automatic - \e{copy on write} operations that members of QSharedDataPointer do, - detach() is \e not called automatically anywhere in the member - functions of this class. If you find that you are calling detach() - everywhere in your code, consider using QSharedDataPointer instead. + Because QExplicitlySharedDataPointer does not do the automatic + \e{copy on write} operations that members of QSharedDataPointer do, + detach() is \e not called automatically anywhere in the member + functions of this class. If you find that you are calling detach() + everywhere in your code, consider using QSharedDataPointer instead. */ /*! \fn T *QExplicitlySharedDataPointer::clone() \since 4.5 - Creates and returns a deep copy of the current data. This function - is called by detach() when the reference count is greater than 1 in - order to create the new copy. This function uses the \e {operator - new} and calls the copy constructor of the type T. + Creates and returns a deep copy of the current data. This function + is called by detach() when the reference count is greater than 1 in + order to create the new copy. This function uses the \e {operator + new} and calls the copy constructor of the type T. - See QSharedDataPointer::clone() for an explanation of how to use it. + See QSharedDataPointer::clone() for an explanation of how to use it. */ /*! - \typedef QExplicitlySharedDataPointer::Type + \typedef QExplicitlySharedDataPointer::Type - This is the type of the shared data object. The \e{d pointer} - points to an object of this type. - */ + This is the type of the shared data object. The \e{d pointer} + points to an object of this type. +*/ QT_END_NAMESPACE |