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List:       kde-commits
Subject:    [gluon] core: core: Improve documentation of Log class
From:       Arjen Hiemstra <ahiemstra () heimr ! nl>
Date:       2014-08-31 22:01:21
Message-ID: E1XODBZ-0003xU-4Y () scm ! kde ! org
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Git commit 6579468d77d368baf624dac1377da61288c9b485 by Arjen Hiemstra.
Committed on 31/08/2014 at 21:55.
Pushed by ahiemstra into branch 'master'.

core: Improve documentation of Log class

M  +41   -0    core/log.h

http://commits.kde.org/gluon/6579468d77d368baf624dac1377da61288c9b485

diff --git a/core/log.h b/core/log.h
index af91599..1181fdb 100644
--- a/core/log.h
+++ b/core/log.h
@@ -45,6 +45,8 @@ namespace GluonCore
 =

     /**
      * The category a message belongs to.
+     *
+     * \todo It probably makes sense to change category to a QByteArray so=
 we have more flexibility.
      */
     enum LogCategory
     {
@@ -74,6 +76,9 @@ namespace GluonCore
 =

     /**
      * Helper class for building a log message to output.
+     *
+     * While it is possible to construct this manually, we recommend using=
 the LOG()
+     * and related macros instead, as they greatly simplify the process.
      */
     class GLUONCORE_EXPORT LogBuilder
     {
@@ -97,6 +102,40 @@ namespace GluonCore
      * to log and where to log to. LogBuilder constructs a LogData object =
that is sent
      * to Log on destruction. Log then outputs the data of that LogData ob=
ject to
      * whatever output was selected.
+     *
+     * There is no way to use the Log class to directly send a message. In=
stead, create
+     * an instance of LogBuilder to add a message. LogBuilder will send th=
e message on
+     * destruction, so it is best to create it on the stack.
+     *
+     * ## LogLevel and LogCategory
+     *
+     * Each message has a level and category. These are used to determine =
whether a
+     * message should be logged at all. During compile time, a maximum log=
 level can
+     * be set using the `GLUON_MAX_LOG_LEVEL` define. This will define a g=
lobal maximum
+     * logging level, anything above that level will be ignored.The value =
of this define
+     * defaults to LogDebug for debug builds and LogWarning for release bu=
ilds.
+     *
+     * In addition, each category can have a different maximum logging lev=
el set at runtime.
+     * If a message is under the maximum log level but over a category's r=
untime defined
+     * maximum log level it is also ignored. Finally, if it passes the che=
ck the category
+     * and log level will be used to print a log message.
+     *
+     * ## Logging Context
+     *
+     * Each message additionally has a context. This is a string used to p=
rovide
+     * context to a message, that is, indicate where the message originate=
d from. The Log
+     * class maintains a stack of contexts. Each time setCurrentContext is=
 called, this
+     * will add a new context to the stack, whereas clearCurrentContext wi=
ll remove the top
+     * context from the stack. The macros DEBUG(), NOTICE(), INFO(), WARNI=
NG(), ERROR() and
+     * CRITICAL() will all provide a default context of file, line and fun=
ction name. The
+     * macros suffixed with _NC will provide an empty context, which means=
 it will use
+     * whatever context is current. This can be used to provide a differen=
t context for
+     * messages not originating from a certain file, like compilation erro=
rs from a script
+     * file pointing to the script file rather than the C++ source file.
+     *
+     * \warning Code supplied to the LOG() related macros may be ignored o=
r even completely
+     * removed depending on the maximum compile and runtime log level. The=
refore, you should
+     * never rely on logging code to perform important function like initi=
alization.
      */
     class GLUONCORE_EXPORT Log : public Singleton< Log >
     {
@@ -215,6 +254,8 @@ namespace GluonCore
 =

 /**
  * A series of macros to output at a certain log level, using the default =
category and an empty context.
+ *
+ * Use these in combination with Log::setCurrentContext() to provide custo=
m contexts, like Asset files.
  */
 #define CRITICAL_NC() LOG( GLUON_DEFAULT_LOG_CATEGORY, GluonCore::LogCriti=
cal, QByteArray() )
 #define ERROR_NC() LOG( GLUON_DEFAULT_LOG_CATEGORY, GluonCore::LogError, Q=
ByteArray() )

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