\helpref{wxLogPassThrough}{wxlogpassthrough},\\
\helpref{wxStreamToTextRedirector}{wxstreamtotextredirector}
\helpref{wxLogPassThrough}{wxlogpassthrough},\\
\helpref{wxStreamToTextRedirector}{wxstreamtotextredirector}
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.
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.
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).
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:
-\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
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
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.
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
\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
(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
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.
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()}
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.
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
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:
\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
\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 \helpful{wxLogChain}{wxlogchain} and
-\helpful{wxLogPassThrough}{wxlogpassthrough} can be used.
+normally. For this the \helpref{wxLogChain}{wxlogchain} and
+\helpref{wxLogPassThrough}{wxlogpassthrough} can be used.
projects / wxWidgets.git / blobdiff