path: root/src/qdoc/doc/qdoc-manual-contextcmds.qdoc

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/*!
    \page 14-qdoc-commands-contextcommands.html
    \previouspage Topic Commands
    \nextpage Document Navigation

    \title Context Commands

    The context commands provide information about the element being
    documented that QDoc can't deduce on its own. For example:
    \list
    \li Is this class thread-safe?
    \li Is this function reentrant?
    \li Of which module is this class a member?
    \li Which include statement is needed to use this class?
    \endlist

    Context commands can appear anywhere in a QDoc comment,
    but they are normally placed near the top of the comment, just
    below the \l {Topic Commands} {topic} command.

    \list
      \li \l {abstract-command} {\\abstract}
      \li \l {ingroup-command}{\\ingroup},
      \li \l {inheaderfile-command}{\\inheaderfile},
      \li \l {inherits-command}{\\inherits},
      \li \l {inmodule-command}{\\inmodule},
      \li \l {internal-command}{\\internal},
      \li \l {nextpage-command}{\\nextpage},
      \li \l {nonreentrant-command}{\\nonreentrant},
      \li \l {obsolete-command}{\\obsolete},
      \li \l {overload-command}{\\overload},
      \li \l {preliminary-command}{\\preliminary},
      \li \l {previouspage-command}{\\previouspage},
      \li \l {qmlabstract-command} {\\qmlabstract}
      \li \l {readonly-command} {\\readonly}
      \li \l {reentrant-command}{\\reentrant},
      \li \l {reimp-command}{\\reimp},
      \li \l {relates-command}{\\relates},
      \li \l {since-command}{\\since},
      \li \l {startpage-command}{\\startpage},
      \li \l {subtitle-command}{\\subtitle}
      \li \l {threadsafe-command}{\\threadsafe},
      \li \l {title-command}{\\title}
    \endlist

*/

/*!
    \page 15-qdoc-commands-navigation.html
    \previouspage Context Commands
    \nextpage Status

    \title Document Navigation

    The navigation commands are for linking the pages of a document in
    a meaningful sequence. Below is a sequence of QDoc comments that
    shows a typical use of the navigation commands.

    \section1 Example
    \quotefile files/basicqt.qdoc.sample

    QDoc renders the "Getting Started" page in \c{creatingdialogs.html}:

    \quotation
    \raw HTML
        <table border="0" cellpadding="0" cellspacing="5" width="100%">

        <tr>
        <p>
        [Previous: <a href="15-qdoc-commands-navigation.html#deadlink">
        Basic Qt</a>]
        [<a href="15-qdoc-commands-navigation.html#deadlink">Contents</a>]
        [Next: <a href="15-qdoc-commands-navigation.html#deadlink">
        Creating Dialogs</a>]
        </p>

        <h1 align="center">Getting Started<br /></h1>

        <p>
        This chapter shows how to combine basic C++ with the
        functionality provided by Qt to create a few small graphical
        interface (GUI) applications.
        </p>

        <p>
        [Previous: <a href="15-qdoc-commands-navigation.html#deadlink">
        Basic Qt</a>]
        [<a href="15-qdoc-commands-navigation.html#deadlink">Contents</a>]
        [Next: <a href="15-qdoc-commands-navigation.html#deadlink">
        Creating Dialogs</a>]
        </p>

        </table>
    \endraw
    \endquotation

    The \l {startpage-command} {\\startpage} command creates a link to
    the page the author wants as the first page of a multipage document.

    The link is included in the generated HTML source code but has no
    visual effect on the documentation:

    \code
    <head>
        ...
        <link rel="start" href="basicqt.html" />
        ...
    </head>
    \endcode

    \section1 Commands

    \target previouspage-command
    \section2 \\previouspage

    The \\previouspage command links the current page to the previous
    page in a sequence.a The command has two arguments, each enclosed
    by curly braces: the first is the link target (the title of
    the previous page), the second is the link text. If the page's
    title is equivalent to the link text, the second argument can be
    omitted.

    The command must stand alone on its own line.

    \target nextpage-command
    \section2 \\nextpage

    The \\nextpage command links the current page to the next page in
    a sequence. The command follows the same syntax and argument
    convention as the \l {previouspage-command} {\\previouspage}
    command.

    \target startpage-command
    \section2 \\startpage

    The \\startpage command specifies the first page of a sequence of
    pages. The command must stand alone on its own line, and its
    unique argument is the title of the first document.

    QDoc will generate a link to the start page and include it in the
    generated HTML file, but this has no visual effect on the
    documentation. The generated link type tells browsers and search
    engines which document is considered by the author to be the
    starting point of the collection.
*/

/*!
    \page 16-qdoc-commands-status.html
    \previouspage Document Navigation
    \nextpage Thread Support

    \title Status

    These commands are for indicating that a documented element has
    some special status. The element could be marked as about to be
    made obsolete, or that it is simply not to be included in the public
    interface. The \l {since-command}{\\since} command is for
    specifying the version number in which a function or class first
    appeared. The \l {qmlabstract-command} {\\qmlabstract} command is
    for marking a QML type as an abstract base class.

    \target abstract-command
    \target qmlabstract-command
    \section1 \\abstract and \\qmlabstract

    \\abstract is a synonym for the \\qmlabstract command. Add this
    command to the \l {qmltype-command} {\\qmltype} comment for a QML
    type when that type is meant to be used \e {only} as an abstract
    base type. When a QML type is abstract, it means that the QML type
    that can't be instantiated. Instead, the properties in its public
    API are included in the public properties list on the reference
    page for each QML type that inherits the abstract QML type. The
    properties are documented as if they are properties of the
    inheriting QML type.

    Normally, when a QML type is marked with \e{\\qmlabstract}, it is
    also marked with \e{\\internal} so that its reference page is not
    generated. It the abstract QML type is not marked internal, it
    will have a reference page in the documentation.

    \target default-command
    \section1 \\default

    The \\default command is for marking a QML property as the
    \l {default-properties}
    {default property}. The word \c default is displayed in
    the documentation of the property.

    \code
    / *!
        \qmlproperty list<Change> State::changes
        This property holds the changes to apply for this state.
        \default

        By default these changes are applied against the default state. If the state
        extends another state, then the changes are applied against the state being
        extended.
    * /
    \endcode

    See how QDoc renders this property on the reference page for the
    \l {State::changes}{State} type.

    \target dontdocument-command
    \section1 \\dontdocument

    The \\dontdocument command is only used in a dontdocument.qdoc file
    for a particular module. This file specifies publically declared
    classes or structs that are not meant to be documented. QDoc will
    not print warnings about missing \\class comments for these classes
    and structs.

    Below you will find the \\dontdocument command in the
    dontdocument.qdoc for widgets:

    \badcode
    / *!
       \dontdocument (QTypeInfo QMetaTypeId)
    * /
    \endcode

    \target inheaderfile-command
    \section1 \\inheaderfile

    The \\inheaderfile meta-command is used for overriding the include statement
    generated for a C++ class, namespace, or header file reference documentation.

    By default, QDoc documents a \c {\class SomeClass} to be available with
    a following include statement:

    \code
    #include <SomeClass>
    \endcode

    If the actual include statement differs from the default, this can be
    documented as

    \badcode
    \class SomeClass
    \inheaderfile Tools/SomeClass
    ...
    \endcode

    See also \l {class-command}{\\class} and
             \l {headerfile-command}{\\headerfile}.

    \target obsolete-command
    \section1 \\obsolete

    The \\obsolete command is for indicating that a function is being
    deprecated, and it should no longer be used in new code. There is
    no guarantee for how long it will remain in the library.

    The \\obsolete command takes no arguments.

    When generating the reference documentation for a class, QDoc will
    create and link to a separate page documenting its obsolete
    functions. Usually an equivalent function is provided as an
    alternative.

    \code
    / *!
        \fn MyClass::MyObsoleteFunction
        \obsolete

        Use MyNewFunction() instead.
    * /
    \endcode

    QDoc renders this in \c{myclass-obsolete.html} as:

    \quotation
        \raw HTML
        <h1>Obsolete Members for MyClass</h1>
        \endraw

        \b {The following class members are obsolete.} They are
        provided to keep old source code working. We strongly advise
        against using them in new code.

        ...

        \list
            \li void MyObsoleteFunction() \c (obsolete)
            \li ...
        \endlist

        \raw HTML
        <hr />
        <h2>Member Function Documentation</h2>
        <h3>void MyObsoleteFunction ()</h3>
        <p>Use MyNewFunction() instead.</p>
        \endraw
        ...
    \endquotation

    \target internal-command
    \section1 \\internal

    The \\internal command indicates that the referenced
    function is not part of the public interface.

    The command must stand on its own line.

    QDoc ignores the documentation as well as the documented item,
    when generating the associated class reference documentation.

    \code
    / *!
        \internal

        Tries to find the decimal separator. If it can't find
        it and the thousand delimiter is != '.' it will try to
        find a '.';
    * /
    int QDoubleSpinBoxPrivate::findDelimiter
            (const QString &str, int index) const
    {
        int dotindex = str.indexOf(delimiter, index);
        if (dotindex == -1 && thousand != dot && delimiter != dot)
            dotindex = str.indexOf(dot, index);
        return dotindex;
    }
    \endcode

    This function will not be included in the documentation.

    \target preliminary-command
    \section1 \\preliminary

    The \\preliminary command is for indicating that a referenced
    function is still under development.

    The command must stand on its own line.

    The \\preliminary command expands to a notification in the
    function documentation, and marks the function as preliminary when
    it appears in lists.

    \code
    / *!
        \preliminary

        Returns information about the joining type attributes of the
        character (needed for certain languages such as Arabic or
        Syriac).

    * /
    QChar::JoiningType QChar::joiningType() const
    {
        return QChar::joiningType(ucs);
    }
    \endcode

    QDoc renders this as:

    \quotation
        \raw HTML
        <h3>
        <a href="http://doc.qt.io/qt-5/qchar.html#JoiningType-enum">JoiningType</a>
        QChar::joiningType() const</h3>
        \endraw

        \b {This function is under development and
        subject to change.}

        Returns information about the joining type attributes of the
        character (needed for certain languages such as Arabic or
        Syriac).
    \endquotation

    And the function's entry in QChar's list of public functions will be
    rendered as:

    \quotation
        \list
        \li ...
        \li JoiningType \l {QChar::joiningType()} {joiningType}() const  \c (preliminary)
       \li ...
       \endlist
    \endquotation

    \target readonly-command
    \section1 \\readonly

    The \\readonly command is used in conjunction with a \l {qmlproperty-command}
    {\\qmlproperty} command to mark the QML property as read-only.

    \target since-command
    \section1 \\since

    The \\since command tells in which minor release
    the associated functionality was added.

    \code
    / *!
        \since 4.1

        Returns an icon for \a standardIcon.

        ...

        \sa standardPixmap()
    * /
    QIcon QStyle::standardIcon(StandardPixmap standardIcon, const QStyleOption *option, const QWidget *widget) const
    {
    }
    \endcode

    QDoc renders this as:

    \quotation
        \raw HTML
        <h3>QIcon QStyle::standardIcon(StandardPixmap standardIcon, const QStyleOption *option, const QWidget *widget) const</h3>
        \endraw

        This function was introduced in Qt version 4.1

        Returns an icon for \a standardIcon.

        ...

        See also \l {QStyle::standardPixmap()} {standardPixmap()}.
    \endquotation

    QDoc generates the "Qt" reference from the \l
    {25-qdoc-configuration-derivedprojects.html#project} {\c project}
    configuration variable. For that reason this reference will change
    according to the current documentation project.

    See also \l {project}
    {\c project}.
*/


/*!
    \page 17-qdoc-commands-thread.html
    \previouspage Status
    \nextpage Relating Things

    \title Thread Support

    The thread support commands are for specifying the level of
    support for multithreaded programming in a class or function.
    There are three levels of support: \c threadsafe, \c reentrant and
    \c nonreentrant.

    The default is \c nonreentrant which means that the associated
    class or function cannot be called by multiple threads. \c
    Reentrant and \c threadsafe are levels primarily used for classes.

    \c Reentrant means that all the functions in the referenced class
    can be called simultaneously by multiple threads, provided that
    each invocation of the functions reference unique data. While \c
    threadsafe means that all the functions in the referenced class
    can be called simultaneously by multiple threads even when each
    invocation references shared data.

    When a class is marked \l {reentrant-command} {\\reentrant} or \l
    {threadsafe-command} {\\threadsafe}, functions in that class can
    be marked \c nonreentrant using the \l {nonreentrant-command}
    {\\nonreentrant} command.

    \section1 Example

    \target reentrant-example
    \code
    \beginqdoc
        \class QLocale
        \brief The QLocale class converts between numbers and their
        string representations in various languages.

        \reentrant
        \ingroup i18n
        \ingroup text

        QLocale is initialized with a language/country pair in its
        constructor and offers number-to-string and string-to-number
        conversion functions similar to those in QString.

        ...

        \nonreentrant

        Sets the global default locale to \a locale. These values are
        used when a QLocale object is constructed with no
        arguments. If this function is not called, the system's locale
        is used.

        \warning In a multithreaded application, the default locale
        should be set at application startup, before any non-GUI
        threads are created.

        \sa system(), c()
    \endqdoc
    void QLocale::setDefault(const QLocale &locale)
    {
        default_d = locale.d;
    }
    \endcode

    QDoc renders this as:

    \quotation
        \raw HTML
            <h1><center>QLocale Class Reference</center></h1>
        \endraw

        The QLocale class converts between numbers and their string
        representations in various languages. More...

        \code
        #include <QLocale>
        \endcode

        \b {Note:} All the functions in this class are \l
        {17-qdoc-commands-thread.html#reentrant} {reentrant}, except \l
        {QLocale::setDefault()} {setDefault()}.

        ...

        \raw HTML
            <hr />
            <h2>Member Type Documentation</h2>
        \endraw

        ...

        \raw HTML
            <h3>void QLocale::setDefault ( const QLocale & locale ) </h3>
        \endraw

        Sets the global default locale to locale. These values are
        used when a QLocale object is constructed with no
        arguments. If this function is not called, the system's locale
        is used.

        \warning In a multithreaded application, the default locale
        should be set at application startup, before any non-GUI
        threads are created.

        \warning This function is not reentrant.

        See also \l {QLocale::system()} {system()} and \l
        {QLocale::c()} {c()}.

        ...
    \endquotation

    As shown above, QDoc generates a notification when a class is
    declared reentrant, and lists the exceptions (the declared
    nonreentrant functions). A link to the general documentation on \l
    {17-qdoc-commands-thread.html#reentrant} {reentrancy and thread-safety} is
    included. In addition a warning, "\b Warning: This function is
    not reentrant.", is generated in the nonreentrant functions'
    documentation.

    QDoc will generate the same notification and warnings when a class
    is declared threadsafe.

    For more information see the general documentation on \l
    {17-qdoc-commands-thread.html#reentrant} {reentrancy and thread-safety}.

    \section1 Commands

    \target threadsafe-command
    \section2 \\threadsafe

    The \\threadsafe command includes a line in the documentation to
    indicate that the associated class or function is \e threadsafe
    and can be called simultaneously by multiple threads, even when
    separate invocations reference shared data.

    The command must stand on its own line.

    The documentation generated from this command will be similar to
    the what is generated for the \l {reentrant-command} {\\reentrant}
    command. See the example above in the \l {reentrant-example}
    {introduction}.

    See also \l{reentrant-command} {\\reentrant} and
    \l{nonreentrant-command} {\\nonreentrant}.

    \target reentrant-command
    \section2 \\reentrant

    The \\reentrant command indicates that the associated class or
    function can be called simultaneously by multiple threads,
    provided that each invocation references its own data. See the \l
    {reentrant-example} {example} above.

    The command must stand on its own line.

    See also \l{nonreentrant-command} {\\nonreentrant} and
    \l{threadsafe-command} {\\threadsafe}.

    \target nonreentrant-command
    \section2 \\nonreentrant

    The \\nonreentrant command indicates that the associated class or
    function cannot be called by multiple threads. Nonreentrant is the
    default case.

    The command must stand on its own line.

    When a class is marked \l {reentrant-command} {\\reentrant} or \l
    {threadsafe-command} {\\threadsafe}, functions in that class can
    be marked \c nonreentrant using this command in the \l{fn-command}
    {\\fn} comment of the functions to be excluded.

    See also \l{reentrant-command} {\\reentrant} and
    \l{threadsafe-command} {\\threadsafe}.
*/

/*!
    \page 18-qdoc-commands-relating.html
    \previouspage Thread Support
    \nextpage Grouping Things

    \title Relating Things

    The relating commands are for specifying how one documented
    element relates to another documented element. Some examples:
    \list
    \li This function is an overload of another function.
    \li This function is a reimplementation of another function.
    \li This typedef is \e related to some class or header file.
    \endlist

    There is also a command for documenting that a QML type inherits
    some other QML type.

    \section1 Commands

    \target inherits-command
    \section2 \\inherits

    The \\inherits command is for documenting that one QML type
    inherits some other QML type. It must be included in the
    inheriting element's \l{qmltype-command}{\\qmltype} comment.
    The argument is the name of the inherited QML type.

    \code
    / *!
        \qmltype PauseAnimation
        \instantiates QDeclarativePauseAnimation
        \ingroup qml-animation-transition
        \since 4.7
        \inherits Animation
        \brief The PauseAnimation element provides a pause for an animation.

        When used in a SequentialAnimation, PauseAnimation is a step
        when nothing happens, for a specified duration.

        A 500ms animation sequence, with a 100ms pause between two animations:

        SequentialAnimation {
            NumberAnimation { ... duration: 200 }
            PauseAnimation { duration: 100 }
            NumberAnimation { ... duration: 200 }
        }

        \sa {QML Animation and Transitions}, {declarative/animation/basics}{Animation basics example}
    * /
    \endcode

    QDoc includes this line on the reference page for the
    \l [QML] PauseAnimation
    element:

    \quotation
        Inherits \l [QML] Animation
    \endquotation

    \target overload-command
    \section2 \\overload

    The \\overload command is for indicating that a function is a
    secondary overload of its name.

    The command must stand on its own line.

    For a function name that is overloaded (except constructors), QDoc
    expects one primary version of the function, and all the others
    marked with the \b {\\overload command}. The primary version
    should be fully documented. Each overload can have whatever extra
    documentation you want to add for just that overloaded version.

    You can include the function name plus '()' as a parameter to
    the \b{\\overload} command, which will include a standard
    \e{This function overloads...}  line of text with a link
    to the documentation for the primary version of the function.

    \code
    / *!
        \overload addAction()

        This convenience function creates a new action with an
        \a icon and some \a text. The function adds the newly
        created action to the menu's list of actions, and
        returns it.

        \sa QWidget::addAction()
    * /
    QAction *QMenu::addAction(const QIcon &icon, const QString &text)
    {
        QAction *ret = new QAction(icon, text, this);
        addAction(ret);
        return ret;
    }
    \endcode

    QDoc renders this as:

    \quotation
        \raw HTML
        <h3><a href="http://doc.qt.io/qt-5/qaction.html">QAction</a>
        * QMenu::addAction ( const QIcon & <i>icon</i>,
        const QString & <i>text</i> )
        </h3>
        \endraw

    This function overloads \l {QMenu::addAction()} {addAction()}

        This convenience function creates a new action with an
        \e icon and some \e text. The function adds the newly
        created action to the menu's list of actions, and
        returns it.

        See also
        \l {QWidget::addAction()} {QWidget::addAction}().
    \endquotation

    If you don't include the function name with the \b{\\overload}
    command, then instead of the "This function overloads..." line
    with the link to the documentation for the primary version, you
    get the old standard line:

    \quotation
        This is an overloaded member function, provided for
        convenience.
    \endquotation.

    \target reimp-command
    \section2 \\reimp

    The \\reimp command is for indicating that a function is a
    reimplementation of a virtual function.

    The command must stand on its own line.

    QDoc will omit the reimplemented function from the class
    reference.

    \code
    / *!
        \reimp
    * /
    void QToolButton::nextCheckState()
    {
        Q_D(QToolButton);
        if (!d->defaultAction)
            QAbstractButton::nextCheckState();
        else
            d->defaultAction->trigger();
    }
    \endcode

    This function will not be included in the documentation. Instead,
    a link to the base function QAbstractButton::nextCheckState() will
    appear in the documentation.

    \target relates-command
    \section2 \\relates

    The \\relates command is for including the documentation of a
    global element to some class or header file. The argument is a
    class name or header file.

    \code
    / *!
        \relates QChar

        Reads a char from the stream \a in into char \a chr.

        \sa {Format of the QDataStream operators}
    * /
    QDataStream &operator>>(QDataStream &in, QChar &chr)
    {
        quint16 u;
        in >> u;
        chr.unicode() = ushort(u);
        return in;
    }
    \endcode

    The documentation for this function will be included on the reference page
    for class QChar.
*/

/*!
    \page 19-qdoc-commands-grouping.html
    \previouspage Relating Things
    \nextpage Naming Things

    \title Grouping Things

    The grouping commands relate classes to defined groups and
    modules. The groups are used when generating lists of related
    classes in the documentation, while the modules are elements of
    Qt's structure.

    \section1 Commands

    \target ingroup-command
    \section2 \\ingroup

    The \\ingroup command indicates that the given
    overview or documented class belongs to a certain group of
    related docmentation.

    A class or overview may belong to many groups.

    The \\ingroup command's argument is a group name, but note
    that the command considers the rest of the line as part of
    its argument. Make sure that the group name is followed by
    a linebreak.

    \code
    / *!
        \class QDir
        \brief The QDir class provides access to directory
               structures and their contents.

        \ingroup io
        ...
    * /
    \endcode

    This will include the QDir class in the \c io group, which means,
    for example, that QDir will appear on the list created by calling
    the \l {group-command} {\\group} command with the \c io argument.

    To list overviews that are related to a certain group, you must
    generate the list explicitly using the \l {generatelist-command}
    {\\generatelist} command with the \c related argument.

    See also \l {group-command} {\\group}.

    \target inmodule-command
    \section2 \\inmodule

    The \\inmodule command relates a class to the module specified by
    the command's argument.

    For the basic classes in Qt, a class's module is determined by its
    location, namely its directory. However, for extensions like
    ActiveQt and Qt Designer, a class must be related to a module
    explicitly.

    The command's argument is a module name, but note that the command
    considers the rest of the line as part of its argument. Make sure
    that the module name is followed by a linebreak.

    \code
    /*!
        \class QDesignerTaskMenuExtension
        \inmodule QtDesigner
    * /
    \endcode

    This ensures that the QDesignerTaskMenuExtension class is included
    in the Qt Designer module, which means, for example, that the
    class will appear on the list created by calling the \l
    {generatelist-command} {\\generatelist} command with the \c
    {{classesbymodule QtDesigner}} argument.

    See also \l {module-command} {\\module} and \l
    {generatelist-command} {\\generatelist}.
*/

/*!
    \page 20-qdoc-commands-namingthings.html
    \previouspage Grouping Things
    \nextpage Markup Commands

    \title Naming Things

    In general, a title command considers everything that follows it
    until the first line break as its argument. If the title is so
    long it must span multiple lines, end each line (except the last
    one) with a backslash.

    \section1 Commands

    \target title-command
    \section2 \\title

    The \\title command sets the title for a documentation page, or
    allows you to override it.

    \code
    / *!
        \page signalandslots.html

        \title Signals & Slots

        Signals and slots are used for communication between
        objects. The signals and slots mechanism is a central
        feature of Qt, and probably the part that differs most
        from the features provided by other frameworks.

        ...
    * /
    \endcode

    QDoc renders this as:

    \quotation
        \raw HTML
            <h1><center>Signal and Slots</center></h1>
        \endraw

        Signals and slots are used for communication between
        objects. The signals and slots mechanism is a central
        feature of Qt and probably the part that differs most
        from the features provided by other frameworks.
        ...
    \endquotation
    See also \l {subtitle-command} {\\subtitle}.

    \target subtitle-command
    \section2 \\subtitle

    The \\subtitle command sets a subtitle for a documentation page.

    \code
    \beginqdoc
        \page qtopiacore-overview.html

        \title Qtopia Core
        \subtitle Qt for Embedded Linux

        Qt/Embedded, the embedded Linux port of Qt, is a
        complete and self-contained C++ GUI and platform
        development tool for Linux-based embedded development.
        ...
    \endqdoc
    \endcode

    QDoc renders this as:

    \quotation
        \raw HTML
            <h1><center>Qtopia Core</center></h1>
            <h2><center>Qt for Embedded Linux</center></h2>
        \endraw

        Qt/Embedded, the embedded Linux port of Qt, is a
        complete and self-contained C++ GUI and platform
        development tool for Linux-based embedded development.
        ...
    \endquotation

    See also \l {title-command} {\\title}.

*/