QMessageLogger Class▲
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Header: QMessageLogger
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CMake:
find_package(Qt6 REQUIRED COMPONENTS Core)
target_link_libraries(mytarget PRIVATE Qt6::Core)
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qmake: QT += core
Detailed Description▲
QMessageLogger is used to generate messages for the Qt logging framework. Usually one uses it through qDebug(), qInfo(), qWarning(), qCritical, or qFatal() functions, which are actually macros: For example qDebug() expands to QMessageLogger(__FILE__, __LINE__, Q_FUNC_INFO).debug() for debug builds, and QMessageLogger(0, 0, 0).debug() for release builds.
One example of direct use is to forward errors that stem from a scripting language, e.g. QML:
void statusChanged(QDeclarativeComponent::Status status) {
if (status == QDeclarativeComponent::Error) {
foreach (const QDeclarativeError &error, component->errors()) {
const QByteArray file = error.url().toEncoded();
QMessageLogger(file.constData(), error.line(), 0).debug() << error.description();
}
}
}See Also▲
Member Type Documentation▲
QMessageLogger::CategoryFunction▲
This is a typedef for a pointer to a function with the following signature:
const QLoggingCategory &category();The Q_DECLARE_LOGGING_CATEGORY macro generates a function declaration with this signature, and Q_LOGGING_CATEGORY generates its definition.
Member Function Documentation▲
[constexpr] QMessageLogger::QMessageLogger()▲
Constructs a default QMessageLogger. See the other constructors to specify context information.
[constexpr] QMessageLogger::QMessageLogger(const char *file, int line, const char *function)▲
Constructs a QMessageLogger to record log messages for file at line in function. The is equivalent to QMessageLogger(file, line, function, "default")
[constexpr] QMessageLogger::QMessageLogger(const char *file, int line, const char *function, const char *category)▲
Constructs a QMessageLogger to record category messages for file at line in function.
void QMessageLogger::critical(const char *msg, ...) const▲
Logs a critical message specified with format msg. Additional parameters, specified by msg, may be used.
See Also▲
See also qCritical()
void QMessageLogger::critical(const QLoggingCategory &cat, const char *msg, ...) const▲
Logs a critical message specified with format msg for the context cat. Additional parameters, specified by msg, may be used.
See Also▲
See also qCCritical()
void QMessageLogger::critical(QMessageLogger::CategoryFunction catFunc, const char *msg, ...) const▲
Logs a critical message specified with format msg for the context returned by catFunc. Additional parameters, specified by msg, may be used.
See Also▲
See also qCCritical()
QDebug QMessageLogger::critical() const▲
QDebug QMessageLogger::critical(const QLoggingCategory &cat) const▲
Logs a critical message into category cat using a QDebug stream.
See Also▲
See also qCCritical(), QDebug
QDebug QMessageLogger::critical(QMessageLogger::CategoryFunction catFunc) const▲
Logs a critical message into category returned by catFunc using a QDebug stream.
See Also▲
See also qCCritical(), QDebug
void QMessageLogger::debug(const char *msg, ...) const▲
Logs a debug message specified with format msg. Additional parameters, specified by msg, may be used.
See Also▲
See also qDebug()
void QMessageLogger::debug(const QLoggingCategory &cat, const char *msg, ...) const▲
Logs a debug message specified with format msg for the context cat. Additional parameters, specified by msg, may be used.
See Also▲
See also qCDebug()
void QMessageLogger::debug(QMessageLogger::CategoryFunction catFunc, const char *msg, ...) const▲
Logs a debug message specified with format msg for the context returned by catFunc. Additional parameters, specified by msg, may be used.
See Also▲
See also qCDebug()
QDebug QMessageLogger::debug() const▲
QDebug QMessageLogger::debug(const QLoggingCategory &cat) const▲
QDebug QMessageLogger::debug(QMessageLogger::CategoryFunction catFunc) const▲
void QMessageLogger::fatal(const char *msg, ...) const▲
Logs a fatal message specified with format msg. Additional parameters, specified by msg, may be used.
See Also▲
See also qFatal()
[since 6.5] void QMessageLogger::fatal(const QLoggingCategory &cat, const char *msg, ...) const▲
Logs a fatal message specified with format msg for the context cat. Additional parameters, specified by msg, may be used.
This function was introduced in Qt 6.5.
See Also▲
See also qCFatal()
[since 6.5] void QMessageLogger::fatal(QMessageLogger::CategoryFunction catFunc, const char *msg, ...) const▲
Logs a fatal message specified with format msg for the context returned by catFunc. Additional parameters, specified by msg, may be used.
This function was introduced in Qt 6.5.
See Also▲
See also qCFatal()
[since 6.5] QDebug QMessageLogger::fatal() const▲
[since 6.5] QDebug QMessageLogger::fatal(const QLoggingCategory &cat) const▲
Logs a fatal message into category cat using a QDebug stream.
This function was introduced in Qt 6.5.
See Also▲
[since 6.5] QDebug QMessageLogger::fatal(QMessageLogger::CategoryFunction catFunc) const▲
Logs a fatal message into category returned by catFunc using a QDebug stream.
This function was introduced in Qt 6.5.
See Also▲
void QMessageLogger::info(const char *msg, ...) const▲
Logs an informational message specified with format msg. Additional parameters, specified by msg, may be used.
See Also▲
See also qInfo()
void QMessageLogger::info(const QLoggingCategory &cat, const char *msg, ...) const▲
Logs an informational message specified with format msg for the context cat. Additional parameters, specified by msg, may be used.
See Also▲
See also qCInfo()
void QMessageLogger::info(QMessageLogger::CategoryFunction catFunc, const char *msg, ...) const▲
Logs an informational message specified with format msg for the context returned by catFunc. Additional parameters, specified by msg, may be used.
See Also▲
See also qCInfo()
QDebug QMessageLogger::info() const▲
QDebug QMessageLogger::info(const QLoggingCategory &cat) const▲
QDebug QMessageLogger::info(QMessageLogger::CategoryFunction catFunc) const▲
void QMessageLogger::warning(const char *msg, ...) const▲
Logs a warning message specified with format msg. Additional parameters, specified by msg, may be used.
See Also▲
See also qWarning()
void QMessageLogger::warning(const QLoggingCategory &cat, const char *msg, ...) const▲
Logs a warning message specified with format msg for the context cat. Additional parameters, specified by msg, may be used.
See Also▲
See also qCWarning()
void QMessageLogger::warning(QMessageLogger::CategoryFunction catFunc, const char *msg, ...) const▲
Logs a warning message specified with format msg for the context returned by catFunc. Additional parameters, specified by msg, may be used.
See Also▲
See also qCWarning()