X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/6e6110ee8194ee39944dffd57cce9f22cd8b961e..60b73526d6797ee466c272dbfca962a230bc5908:/docs/latex/wx/tlog.tex diff --git a/docs/latex/wx/tlog.tex b/docs/latex/wx/tlog.tex index 0cb7fccfcf..8799686e8f 100644 --- a/docs/latex/wx/tlog.tex +++ b/docs/latex/wx/tlog.tex @@ -1,11 +1,15 @@ -\section{Log classes overview}\label{wxlogoverview} +\section{wxLog classes overview}\label{wxlogoverview} -Classes: \helpref{wxLog}{wxlog} - -%\helpref{wxLogStderr}{wxlogstderr},% -%\helpref{wxLogOstream}{wxlogostream}, \helpref{wxLogTextCtrl}{wxlogtextctrl},% -%\helpref{wxLogWindow}{wxlogwindow}, \helpref{wxLogGui}{wxloggui},% -%\helpref{wxLogNull}{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 logging here has a broad sense, including all of the program output, not only @@ -33,7 +37,7 @@ appear in a message box by default (but it can be changed, see below). Notice that the standard behaviour is to not show informational messages if there are any errors later - the logic being that the later error messages make the informational messages preceding them meaningless. -\item{\bf wxLogVerbose} is for verbose output. Normally, it's suppressed, but +\item{\bf wxLogVerbose} is for verbose output. Normally, it is suppressed, but might be activated if the user wishes to know more details about the program progress (another, but possibly confusing name for the same function is {\bf wxLogInfo}). @@ -43,11 +47,14 @@ bar of the active or specified (as the first argument) \helpref{wxFrame}{wxframe 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 explitly as the +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). +{\bf Tip:} under Windows, you must either run the program under debugger or +use a 3rd party program such as \urlref{DbgView}{http://www.sysinternals.com} +to actually see the debug output. \item{\bf wxLogTrace} as {\bf wxLogDebug} only does something in debug build. The reason for making it a separate function from it is that usually there are a lot of trace messages, so it might make sense to separate them @@ -63,12 +70,25 @@ generic mechanisms, but are not really adapted for wxWindows, while the log classes are. Some of advantages in using wxWindows log functions are: \begin{itemize}\itemsep=0pt -\item{\bf Portability} It's a common practice to use {\it printf()} statements or +\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()}. + +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} +} + +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 @@ -90,10 +110,10 @@ 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. -wxWindows has the notion of a {\it log target}: it's just a class deriving +wxWindows 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()} +is {\it active} at any moment, this is the one used by {\it wxLogXXX()} functions. The normal usage of a log object (i.e. object of a class derived from wxLog) is to install it as the active target with a call to {\it SetActiveTarget()} and it will be used automatically by all subsequent calls @@ -117,7 +137,7 @@ 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 -applications (it's used by default if you don't do anything) and provides the +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 collects all messages generated by the application and also passes them to the @@ -126,8 +146,8 @@ clear the log, close it completely or save all messages to file. \item{\bf wxLogNull} The last log class is quite particular: it doesn't do anything. The objects of this class may be instantiated to (temporarily) suppress output of {\it wxLogXXX()} functions. As an example, trying to open a -non-existing file will usually provoke an error message, but if you for some -reason it's 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 \begin{verbatim} @@ -145,3 +165,8 @@ reason it's 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 +normally. For this the \helpref{wxLogChain}{wxlogchain} and +\helpref{wxLogPassThrough}{wxlogpassthrough} can be used. +