#include <wx/log.h>
wxLog class defines the interface for the log targets used by wxWidgets logging functions as explained in the wxLog Classes Overview.
The only situations when you need to directly use this class is when you want to derive your own log target because the existing ones don't satisfy your needs. Another case is if you wish to customize the behaviour of the standard logging classes (all of which respect the wxLog settings): for example, set which trace messages are logged and which are not or change (or even remove completely) the timestamp on the messages.
Otherwise, it is completely hidden behind the wxLogXXX() functions and you may not even know about its existence.
stderr
when wxUSE_GUI
= 0.There are several methods which may be overridden in the derived class to customize log messages handling: DoLogRecord(), DoLogTextAtLevel() and DoLogText().
The last method is the simplest one: you should override it if you simply want to redirect the log output elsewhere, without taking into account the level of the message. If you do want to handle messages of different levels differently, then you should override DoLogTextAtLevel().
Finally, if more control over the output format is needed, then the first function must be overridden as it allows to construct custom messages depending on the log level or even do completely different things depending on the message severity (for example, throw away all messages except warnings and errors, show warnings on the screen and forward the error messages to the user's (or programmer's) cell phone -- maybe depending on whether the timestamp tells us if it is day or night in the current time zone).
There also functions to support message buffering. Why are they needed? Some of wxLog implementations, most notably the standard wxLogGui class, buffer the messages (for example, to avoid showing the user a zillion of modal message boxes one after another -- which would be really annoying).
Flush() shows them all and clears the buffer contents. This function doesn't do anything if the buffer is already empty.
Notice that the use of log trace masks is hardly necessary any longer in current wxWidgets version as the same effect can be achieved by using different log components for different log statements of any level. Please see Log Messages Selection for more information about the log components.
The functions below allow some limited customization of wxLog behaviour without writing a new log target class (which, aside from being a matter of several minutes, allows you to do anything you want). The verbose messages are the trace messages which are not disabled in the release mode and are generated by wxLogVerbose(). They are not normally shown to the user because they present little interest, but may be activated, for example, in order to help the user find some program problem.
As for the (real) trace messages, their handling depends on the currently enabled trace masks: if AddTraceMask() was called for the mask of the given message, it will be logged, otherwise nothing happens.
For example,
wxLogTrace( wxTRACE_OleCalls, "IFoo::Bar() called" );
will log the message if it was preceded by:
wxLog::AddTraceMask( wxTRACE_OleCalls);
The standard trace masks are given in wxLogTrace() documentation.
Finally, the wxLog::DoLog() function automatically prepends a time stamp to all the messages. The format of the time stamp may be changed: it can be any string with % specifications fully described in the documentation of the standard strftime() function. For example, the default format is "[%d/%b/%y %H:%M:%S] " which gives something like "[17/Sep/98 22:10:16] " (without quotes) for the current date. Setting an empty string as the time format or calling the shortcut wxLog::DisableTimestamp(), disables timestamping of the messages completely.
See also
The functions in this section work with and manipulate the active log target.
Get/Set methods are used to install/query the current active target and, finally, DontCreateOnDemand() disables the automatic creation of a standard log target if none actually exists. It is only useful when the application is terminating and shouldn't be used in other situations because it may easily lead to a loss of messages.
See also:
Public Member Functions | |
virtual void | Flush () |
Shows all the messages currently in buffer and clears it. | |
void | LogRecord (wxLogLevel level, const wxString &msg, time_t timestamp) |
Log the given record. | |
Static Public Member Functions | |
static void | AddTraceMask (const wxString &mask) |
Add the mask to the list of allowed masks for wxLogTrace(). | |
static void | ClearTraceMasks () |
Removes all trace masks previously set with AddTraceMask(). | |
static void | DontCreateOnDemand () |
Instructs wxLog to not create new log targets on the fly if there is none currently. | |
static bool | EnableLogging (bool enable=true) |
Globally enable or disable logging. | |
static void | FlushActive () |
Flushes the current log target if any, does nothing if there is none. | |
static wxLog * | GetActiveTarget () |
Returns the pointer to the active log target (may be NULL). | |
static wxLogLevel | GetLogLevel () |
Returns the current log level limit. | |
static bool | GetRepetitionCounting () |
Returns whether the repetition counting mode is enabled. | |
static const wxString & | GetTimestamp () |
Returns the current timestamp format string. | |
static wxTraceMask | GetTraceMask () |
static const wxArrayString & | GetTraceMasks () |
Returns the currently allowed list of string trace masks. | |
static bool | GetVerbose () |
Returns whether the verbose mode is currently active. | |
static bool | IsAllowedTraceMask (const wxString &mask) |
Returns true if the mask is one of allowed masks for wxLogTrace(). | |
static bool | IsEnabled () |
Returns true if logging is enabled at all now. | |
static bool | IsLevelEnabled (wxLogLevel level, wxString component) |
Returns true if logging at this level is enabled for the current thread. | |
static void | RemoveTraceMask (const wxString &mask) |
Remove the mask from the list of allowed masks for wxLogTrace(). | |
static void | Resume () |
Resumes logging previously suspended by a call to Suspend(). | |
static wxLog * | SetActiveTarget (wxLog *logtarget) |
Sets the specified log target as the active one. | |
static void | SetComponentLevel (const wxString &component, wxLogLevel level) |
Sets the log level for the given component. | |
static void | SetLogLevel (wxLogLevel logLevel) |
Specifies that log messages with level greater (numerically) than logLevel should be ignored and not sent to the active log target. | |
static void | SetRepetitionCounting (bool repetCounting=true) |
Enables logging mode in which a log message is logged once, and in case exactly the same message successively repeats one or more times, only the number of repetitions is logged. | |
static wxLog * | SetThreadActiveTarget (wxLog *logger) |
Sets a thread-specific log target. | |
static void | SetTimestamp (const wxString &format) |
Sets the timestamp format prepended by the default log targets to all messages. | |
static void | DisableTimestamp () |
Disables time stamping of the log messages. | |
static void | SetTraceMask (wxTraceMask mask) |
static void | SetVerbose (bool verbose=true) |
Activates or deactivates verbose mode in which the verbose messages are logged as the normal ones instead of being silently dropped. | |
static void | Suspend () |
Suspends the logging until Resume() is called. | |
Protected Member Functions | |
Logging callbacks. | |
The functions which should be overridden by custom log targets. When defining a new log target, you have a choice between overriding DoLogRecord(), which provides maximal flexibility, DoLogTextAtLevel() which can be used if you don't intend to change the default log messages formatting but want to handle log messages of different levels differently or, in the simplest case, DoLogText(). | |
virtual void | DoLogRecord (wxLogLevel level, const wxString &msg, const wxLogRecordInfo &info) |
Called to created log a new record. | |
virtual void | DoLogTextAtLevel (wxLogLevel level, const wxString &msg) |
Called to log the specified string at given level. | |
virtual void | DoLogText (const wxString &msg) |
Called to log the specified string. |
static void wxLog::AddTraceMask | ( | const wxString & | mask | ) | [static] |
Add the mask to the list of allowed masks for wxLogTrace().
static void wxLog::ClearTraceMasks | ( | ) | [static] |
Removes all trace masks previously set with AddTraceMask().
static void wxLog::DisableTimestamp | ( | ) | [static] |
Disables time stamping of the log messages.
virtual void wxLog::DoLogRecord | ( | wxLogLevel | level, | |
const wxString & | msg, | |||
const wxLogRecordInfo & | info | |||
) | [protected, virtual] |
Called to created log a new record.
Any log message created by wxLogXXX() functions is passed to this method of the active log target. The default implementation prepends the timestamp and, for some log levels (e.g. error and warning), the corresponding prefix to msg and passes it to DoLogTextAtLevel().
You may override this method to implement custom formatting of the log messages or to implement custom filtering of log messages (e.g. you could discard all log messages coming from the given source file).
virtual void wxLog::DoLogText | ( | const wxString & | msg | ) | [protected, virtual] |
Called to log the specified string.
A simple implementation might just send the string to stdout
or stderr
or save it in a file (of course, the already existing wxLogStderr can be used for this).
The base class version of this function asserts so it must be overridden if you don't override DoLogRecord() or DoLogTextAtLevel().
virtual void wxLog::DoLogTextAtLevel | ( | wxLogLevel | level, | |
const wxString & | msg | |||
) | [protected, virtual] |
Called to log the specified string at given level.
The base class versions logs debug and trace messages on the system default debug output channel and passes all the other messages to DoLogText().
static void wxLog::DontCreateOnDemand | ( | ) | [static] |
Instructs wxLog to not create new log targets on the fly if there is none currently.
(Almost) for internal use only: it is supposed to be called by the application shutdown code.
Note that this function also calls ClearTraceMasks().
static bool wxLog::EnableLogging | ( | bool | enable = true |
) | [static] |
Globally enable or disable logging.
Calling this function with false argument disables all log messages for the current thread.
virtual void wxLog::Flush | ( | ) | [virtual] |
Shows all the messages currently in buffer and clears it.
If the buffer is already empty, nothing happens.
If you override this method in a derived class, call the base class version first, before doing anything else.
Reimplemented in wxLogGui, and wxLogBuffer.
static void wxLog::FlushActive | ( | ) | [static] |
Flushes the current log target if any, does nothing if there is none.
When this method is called from the main thread context, it also flushes any previously buffered messages logged by the other threads. When it is called from the other threads it simply calls Flush() on the currently active log target, so it mostly makes sense to do this if a thread has its own logger set with SetThreadActiveTarget().
static wxLog* wxLog::GetActiveTarget | ( | ) | [static] |
Returns the pointer to the active log target (may be NULL).
Notice that if SetActiveTarget() hadn't been previously explicitly called, this function will by default try to create a log target by calling wxAppTraits::CreateLogTarget() which may be overridden in a user-defined traits class to change the default behaviour. You may also call DontCreateOnDemand() to disable this behaviour.
When this function is called from threads other than main one, auto-creation doesn't happen. But if the thread has a thread-specific log target previously set by SetThreadActiveTarget(), it is returned instead of the global one. Otherwise, the global log target is returned.
static wxLogLevel wxLog::GetLogLevel | ( | ) | [static] |
Returns the current log level limit.
All messages at levels strictly greater than the value returned by this function are not logged at all.
static bool wxLog::GetRepetitionCounting | ( | ) | [static] |
Returns whether the repetition counting mode is enabled.
static const wxString& wxLog::GetTimestamp | ( | ) | [static] |
Returns the current timestamp format string.
static wxTraceMask wxLog::GetTraceMask | ( | ) | [static] |
static const wxArrayString& wxLog::GetTraceMasks | ( | ) | [static] |
Returns the currently allowed list of string trace masks.
static bool wxLog::GetVerbose | ( | ) | [static] |
Returns whether the verbose mode is currently active.
static bool wxLog::IsAllowedTraceMask | ( | const wxString & | mask | ) | [static] |
Returns true if the mask is one of allowed masks for wxLogTrace().
See also: AddTraceMask(), RemoveTraceMask()
static bool wxLog::IsEnabled | ( | ) | [static] |
Returns true if logging is enabled at all now.
static bool wxLog::IsLevelEnabled | ( | wxLogLevel | level, | |
wxString | component | |||
) | [static] |
Returns true if logging at this level is enabled for the current thread.
This function only returns true if logging is globally enabled and if level is less than or equal to the maximal log level enabled for the given component.
void wxLog::LogRecord | ( | wxLogLevel | level, | |
const wxString & | msg, | |||
time_t | timestamp | |||
) |
Log the given record.
This function should only be called from the DoLog() implementations in the derived classes if they need to call DoLogRecord() on another log object (they can, of course, just use wxLog::DoLogRecord() call syntax to call it on the object itself). It should not be used for logging new messages which can be only sent to the currently active logger using OnLog() which also checks if the logging (for this level) is enabled while this method just directly calls DoLog().
Example of use of this class from wxLogChain:
void wxLogChain::DoLogRecord(wxLogLevel level, const wxString& msg, const wxLogRecordInfo& info) { // let the previous logger show it if ( m_logOld && IsPassingMessages() ) m_logOld->LogRecord(level, msg, info); // and also send it to the new one if ( m_logNew && m_logNew != this ) m_logNew->LogRecord(level, msg, info); }
static void wxLog::RemoveTraceMask | ( | const wxString & | mask | ) | [static] |
Remove the mask from the list of allowed masks for wxLogTrace().
static void wxLog::Resume | ( | ) | [static] |
Resumes logging previously suspended by a call to Suspend().
All messages logged in the meanwhile will be flushed soon.
Sets the specified log target as the active one.
Returns the pointer to the previous active log target (may be NULL). To suppress logging use a new instance of wxLogNull not NULL. If the active log target is set to NULL a new default log target will be created when logging occurs.
static void wxLog::SetComponentLevel | ( | const wxString & | component, | |
wxLogLevel | level | |||
) | [static] |
Sets the log level for the given component.
For example, to disable all but error messages from wxWidgets network classes you may use
wxLog::SetComponentLevel("wx/net", wxLOG_Error);
SetLogLevel() may be used to set the global log level.
component | Non-empty component name, possibly using slashes (/ ) to separate it into several parts. | |
level | Maximal level of log messages from this component which will be handled instead of being simply discarded. |
static void wxLog::SetLogLevel | ( | wxLogLevel | logLevel | ) | [static] |
Specifies that log messages with level greater (numerically) than logLevel should be ignored and not sent to the active log target.
static void wxLog::SetRepetitionCounting | ( | bool | repetCounting = true |
) | [static] |
Enables logging mode in which a log message is logged once, and in case exactly the same message successively repeats one or more times, only the number of repetitions is logged.
Sets a thread-specific log target.
The log target passed to this function will be used for all messages logged by the current thread using the usual wxLog functions. This shouldn't be called from the main thread which never uses a thread- specific log target but can be used for the other threads to handle thread logging completely separately; instead of buffering thread log messages in the main thread logger.
Notice that unlike for SetActiveTarget(), wxWidgets does not destroy the thread-specific log targets when the thread terminates so doing this is your responsibility.
This method is only available if wxUSE_THREADS
is 1, i.e. wxWidgets was compiled with threads support.
logger | The new thread-specific log target, possibly NULL. |
static void wxLog::SetTimestamp | ( | const wxString & | format | ) | [static] |
Sets the timestamp format prepended by the default log targets to all messages.
The string may contain any normal characters as well as % prefixed format specificators, see strftime() manual for details. Passing an empty string to this function disables message time stamping.
static void wxLog::SetTraceMask | ( | wxTraceMask | mask | ) | [static] |
static void wxLog::SetVerbose | ( | bool | verbose = true |
) | [static] |
Activates or deactivates verbose mode in which the verbose messages are logged as the normal ones instead of being silently dropped.
static void wxLog::Suspend | ( | ) | [static] |
Suspends the logging until Resume() is called.
Note that the latter must be called the same number of times as the former to undo it, i.e. if you call Suspend() twice you must call Resume() twice as well.
Note that suspending the logging means that the log sink won't be be flushed periodically, it doesn't have any effect if the current log target does the logging immediately without waiting for Flush() to be called (the standard GUI log target only shows the log dialog when it is flushed, so Suspend() works as expected with it).
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