don't always erase the background ourselves as this is incompatible with XP themed...

[wxWidgets.git] / docs / latex / wx / tlog.tex

diff --git a/docs/latex/wx/tlog.tex b/docs/latex/wx/tlog.tex
index 22c9b78ceb618ef1bb4d85537a5d5d7e07f48bfe..e0d6b8a35d72996c17343e5820d90f10d921acdc 100644 (file)
--- a/docs/latex/wx/tlog.tex
+++ b/docs/latex/wx/tlog.tex
@@ -1,24 +1,34 @@
 \section{wxLog classes overview}\label{wxlogoverview}
 
 \section{wxLog classes overview}\label{wxlogoverview}
 

-Classes: \helpref{wxLog}{wxlog}, wxLogStderr,
-wxLogOstream, wxLogTextCtrl, wxLogWindow, wxLogGui, wxLogNull
+Classes: \helpref{wxLog}{wxlog},\\
+\helpref{wxLogStderr}{wxlogstderr},\\
+\helpref{wxLogStream}{wxlogstream},\\
+\helpref{wxLogTextCtrl}{wxlogtextctrl},\\
+\helpref{wxLogWindow}{wxlogwindow},\\
+\helpref{wxLogGui}{wxloggui},\\
+\helpref{wxLogNull}{wxlognull},\\
+\helpref{wxLogChain}{wxlogchain},\\
+\helpref{wxLogPassThrough}{wxlogpassthrough},\\
+\helpref{wxStreamToTextRedirector}{wxstreamtotextredirector}

 
 

-This is a general overview of logging classes provided by wxWindows. The word
+This is a general overview of logging classes provided by wxWidgets. The word

 logging here has a broad sense, including all of the program output, not only
 logging here has a broad sense, including all of the program output, not only

-non interactive messages. The logging facilities included in wxWindows provide
+non interactive messages. The logging facilities included in wxWidgets provide

 the base {\it wxLog} class which defines the standard interface for a {\it log
 target} as well as several standard implementations of it and a family of
 functions to use with them.
 
 First of all, no knowledge of {\it wxLog} classes is needed to use them. For
 this, you should only know about {\it wxLogXXX()} functions. All of them have
 the base {\it wxLog} class which defines the standard interface for a {\it log
 target} as well as several standard implementations of it and a family of
 functions to use with them.
 
 First of all, no knowledge of {\it wxLog} classes is needed to use them. For
 this, you should only know about {\it wxLogXXX()} functions. All of them have

-the same syntax as {\it printf()}, i.e. they take the format string as the
-first argument and a variable number of arguments. Here are all of them:
+the same syntax as {\it printf()} or {\it vprintf()} , i.e. they take the
+format string as the first argument and respectively a variable number of
+arguments or a variable argument list pointer. Here are all of them:

 
 \begin{itemize}\itemsep=0pt
 \item{\bf wxLogFatalError} which is like {\it wxLogError}, but also
 
 \begin{itemize}\itemsep=0pt
 \item{\bf wxLogFatalError} which is like {\it wxLogError}, but also

-terminates the program with the exit code 3 (using {\it abort()} standard
-function also terminates the program with this exit code).
+terminates the program with the exit code $3$ (using {\it abort()} standard
+function). Unlike for all the other logging functions, this function can't be
+overridden by a log target.

 \item{\bf wxLogError} is the function to use for error messages, i.e. the
 messages that must be shown to the user. The default processing is to pop up a
 message box to inform the user about it.
 \item{\bf wxLogError} is the function to use for error messages, i.e. the
 messages that must be shown to the user. The default processing is to pop up a
 message box to inform the user about it.


@@ -35,12 +45,12 @@ progress (another, but possibly confusing name for the same function is {\bf
 wxLogInfo}).
 \item{\bf wxLogStatus} is for status messages - they will go into the status
 bar of the active or specified (as the first argument) \helpref{wxFrame}{wxframe} if it has one.
 wxLogInfo}).
 \item{\bf wxLogStatus} is for status messages - they will go into the status
 bar of the active or specified (as the first argument) \helpref{wxFrame}{wxframe} if it has one.

-\item{\bf wxLogSysError} is mostly used by wxWindows itself, but might be
+\item{\bf wxLogSysError} is mostly used by wxWidgets itself, but might be

 handy for logging errors after system call (API function) failure. It logs the
 specified message text as well as the last system error
 handy for logging errors after system call (API function) failure. It logs the
 specified message text as well as the last system error

-code ({\it errno} or {\it ::GetLastError()} depending on the platform) and the corresponding error
-message. The second form of this function takes the error code explicitly as the
-first argument.
+code ({\it errno} or {\it ::GetLastError()} depending on the platform) and
+the corresponding error message. The second form of this function takes the
+error code explicitly as the first argument.

 \item{\bf wxLogDebug} is {\bf the} right function for debug output. It only
 does anything at all in the debug mode (when the preprocessor symbol
 \_\_WXDEBUG\_\_ is defined) and expands to nothing in release mode (otherwise).
 \item{\bf wxLogDebug} is {\bf the} right function for debug output. It only
 does anything at all in the debug mode (when the preprocessor symbol
 \_\_WXDEBUG\_\_ is defined) and expands to nothing in release mode (otherwise).


@@ -58,36 +68,29 @@ to further restrict the amount of messages generated.
 The usage of these functions should be fairly straightforward, however it may
 be asked why not use the other logging facilities, such as C standard stdio
 functions or C++ streams. The short answer is that they're all very good
 The usage of these functions should be fairly straightforward, however it may
 be asked why not use the other logging facilities, such as C standard stdio
 functions or C++ streams. The short answer is that they're all very good

-generic mechanisms, but are not really adapted for wxWindows, while the log
-classes are. Some of advantages in using wxWindows log functions are:
+generic mechanisms, but are not really adapted for wxWidgets, while the log
+classes are. Some of advantages in using wxWidgets log functions are:

 
 \begin{itemize}\itemsep=0pt
 
 \begin{itemize}\itemsep=0pt

-\item{\bf Portability} It is a common practice to use {\it printf()} statements or
-cout/cerr C++ streams for writing out some (debug or otherwise) information.
+\item{\bf Portability} It is a common practice to use {\it printf()}
+statements or cout/cerr C++ streams for writing out some (debug or otherwise)
+information.

 Although it works just fine under Unix, these messages go strictly nowhere
 under Windows where the stdout of GUI programs is not assigned to anything.
 Thus, you might view {\it wxLogMessage()} as a simple substitute for {\it
 printf()}.
 
 Although it works just fine under Unix, these messages go strictly nowhere
 under Windows where the stdout of GUI programs is not assigned to anything.
 Thus, you might view {\it wxLogMessage()} as a simple substitute for {\it
 printf()}.
 

-Moreover {\it wxMSW} doesn't have a {\bf console} as you may have with {\it
-  wxGTK}. Under {\it wxMSW}, a call using {\it cout} just goes nowhere. To
-cope with this problem, {\it wxWindows} provides a way to redirect {\it cout}
-calls to \helpref{wxTextCtrl}{wxtextctrl}, {\it i.e.}:
-{\small
-\begin{verbatim}
-  wxLogWindow *logger=new wxLogWindow(your_frame,"Logger");
-  cout=*new ostream(logger->GetTextCtrl());
-  wxLog::SetActiveTarget(logger);
-\end{verbatim}
-}
-On the opposite, if you like your {\it wxLogXXX} calls to behave as a {\it cout} 
-call does, just write :
+You can also redirect the {\it wxLogXXX} calls to {\it cout} by just writing:

 {\small
 \begin{verbatim}
   wxLog *logger=new wxLogStream(&cout);
   wxLog::SetActiveTarget(logger);
 \end{verbatim}
 }
 {\small
 \begin{verbatim}
   wxLog *logger=new wxLogStream(&cout);
   wxLog::SetActiveTarget(logger);
 \end{verbatim}
 }

+
+Finally, there is also a possibility to redirect the output sent to {\it cout} 
+to a \helpref{wxTextCtrl}{wxtextctrl} by using the 
+\helpref{wxStreamToTextRedirector}{wxstreamtotextredirector} class.

 \item{\bf Flexibility} The output of wxLog functions can be redirected or
 suppressed entirely based on their importance, which is either impossible or
 difficult to do with traditional methods. For example, only error messages, or
 \item{\bf Flexibility} The output of wxLog functions can be redirected or
 suppressed entirely based on their importance, which is either impossible or
 difficult to do with traditional methods. For example, only error messages, or


@@ -96,10 +99,10 @@ informational messages.
 \item{\bf Completeness} Usually, an error message should be presented to the user
 when some operation fails. Let's take a quite simple but common case of a file
 error: suppose that you're writing your data file on disk and there is not
 \item{\bf Completeness} Usually, an error message should be presented to the user
 when some operation fails. Let's take a quite simple but common case of a file
 error: suppose that you're writing your data file on disk and there is not

-enough space. The actual error might have been detected inside wxWindows code
+enough space. The actual error might have been detected inside wxWidgets code

 (say, in {\it wxFile::Write}), so the calling function doesn't really know the
 exact reason of the failure, it only knows that the data file couldn't be
 (say, in {\it wxFile::Write}), so the calling function doesn't really know the
 exact reason of the failure, it only knows that the data file couldn't be

-written to the disk. However, as wxWindows uses {\it wxLogError()} in this
+written to the disk. However, as wxWidgets uses {\it wxLogError()} in this

 situation, the exact error code (and the corresponding error message) will be
 given to the user together with "high level" message about data file writing
 error.
 situation, the exact error code (and the corresponding error message) will be
 given to the user together with "high level" message about data file writing
 error.


@@ -109,7 +112,7 @@ After having enumerated all the functions which are normally used to log the
 messages, and why would you want to use them we now describe how all this
 works.
 
 messages, and why would you want to use them we now describe how all this
 works.
 

-wxWindows has the notion of a {\it log target}: it is just a class deriving
+wxWidgets has the notion of a {\it log target}: it is just a class deriving

 from \helpref{wxLog}{wxlog}. As such, it implements the virtual functions of
 the base class which are called when a message is logged. Only one log target
 is {\it active} at any moment, this is the one used by {\it wxLogXXX()}
 from \helpref{wxLog}{wxlog}. As such, it implements the virtual functions of
 the base class which are called when a message is logged. Only one log target
 is {\it active} at any moment, this is the one used by {\it wxLogXXX()}


@@ -135,7 +138,7 @@ also be used without any change. There are:
 stderr by default as its name suggests.
 \item{\bf wxLogStream} This class has the same functionality as wxLogStderr,
 but uses {\it ostream} and cerr instead of {\it FILE *} and stderr.
 stderr by default as its name suggests.
 \item{\bf wxLogStream} This class has the same functionality as wxLogStderr,
 but uses {\it ostream} and cerr instead of {\it FILE *} and stderr.

-\item{\bf wxLogGui} This is the standard log target for wxWindows
+\item{\bf wxLogGui} This is the standard log target for wxWidgets

 applications (it is used by default if you don't do anything) and provides the
 most reasonable handling of all types of messages for given platform.
 \item{\bf wxLogWindow} This log target provides a "log console" which
 applications (it is used by default if you don't do anything) and provides the
 most reasonable handling of all types of messages for given platform.
 \item{\bf wxLogWindow} This log target provides a "log console" which


@@ -148,7 +151,7 @@ suppress output of {\it wxLogXXX()} functions. As an example, trying to open a
 non-existing file will usually provoke an error message, but if for some
 reasons it is unwanted, just use this construction:
 
 non-existing file will usually provoke an error message, but if for some
 reasons it is unwanted, just use this construction:
 

-{\small
+{\small%

 \begin{verbatim}
   wxFile file;
 
 \begin{verbatim}
   wxFile file;
 


@@ -161,6 +164,11 @@ reasons it is unwanted, just use this construction:
   
   wxLogMessage("..."); // ok
 \end{verbatim}
   
   wxLogMessage("..."); // ok
 \end{verbatim}

-}
+}%

 \end{itemize}
 
 \end{itemize}
 

+The log targets can also be combined: for example you may wish to redirect the
+messages somewhere else (for example, to a log file) but also process them as
+normally. For this the \helpref{wxLogChain}{wxlogchain} and 
+\helpref{wxLogPassThrough}{wxlogpassthrough} can be used.
+