removed useless spaces
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@51911 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
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@@ -7,29 +7,31 @@
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/////////////////////////////////////////////////////////////////////////////
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/*!
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@page log_overview wxLog classes overview
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Classes: #wxLog,
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#wxLogStderr,
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#wxLogStream,
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#wxLogTextCtrl,
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#wxLogWindow,
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#wxLogGui,
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#wxLogNull,
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#wxLogBuffer,
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#wxLogChain,
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#wxLogInterposer,
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#wxLogInterposerTemp,
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#wxStreamToTextRedirector
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This is a general overview of logging classes provided by wxWidgets. The word
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logging here has a broad sense, including all of the program output, not only
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@@ -42,8 +44,8 @@
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the same syntax as @e printf() or @e vprintf() , i.e. they take the
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format string as the first argument and respectively a variable number of
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arguments or a variable argument list pointer. Here are all of them:
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@b wxLogFatalError which is like @e wxLogError, but also
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terminates the program with the exit code 3 (using @e abort() standard
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function). Unlike for all the other logging functions, this function can't be
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@@ -70,7 +72,7 @@
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does anything at all in the debug mode (when the preprocessor symbol
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__WXDEBUG__ is defined) and expands to nothing in release mode (otherwise).
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@b Tip: under Windows, you must either run the program under debugger or
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use a 3rd party program such as #DbgView
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use a 3rd party program such as #DbgView
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to actually see the debug output.
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@b wxLogTrace as @b wxLogDebug only does something in debug
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build. The reason for making it a separate function from it is that usually
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@@ -78,15 +80,15 @@
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from other debug messages which would be flooded in them. Moreover, the second
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version of this function takes a trace mask as the first argument which allows
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to further restrict the amount of messages generated.
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The usage of these functions should be fairly straightforward, however it may
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be asked why not use the other logging facilities, such as C standard stdio
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functions or C++ streams. The short answer is that they're all very good
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generic mechanisms, but are not really adapted for wxWidgets, while the log
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classes are. Some of advantages in using wxWidgets log functions are:
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@b Portability It is a common practice to use @e printf()
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statements or cout/cerr C++ streams for writing out some (debug or otherwise)
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information.
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@@ -94,16 +96,16 @@
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under Windows where the stdout of GUI programs is not assigned to anything.
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Thus, you might view @e wxLogMessage() as a simple substitute for @e printf().
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You can also redirect the @e wxLogXXX calls to @e cout by just writing:
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@code
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wxLog *logger=new wxLogStream();
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wxLog::SetActiveTarget(logger);
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@endcode
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Finally, there is also a possibility to redirect the output sent to @e cout
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to a #wxTextCtrl by using the
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Finally, there is also a possibility to redirect the output sent to @e cout
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to a #wxTextCtrl by using the
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#wxStreamToTextRedirector class.
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@b Flexibility The output of wxLog functions can be redirected or
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suppressed entirely based on their importance, which is either impossible or
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@@ -120,8 +122,8 @@
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situation, the exact error code (and the corresponding error message) will be
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given to the user together with "high level" message about data file writing
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error.
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After having enumerated all the functions which are normally used to log the
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messages, and why would you want to use them we now describe how all this
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works.
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@@ -142,8 +144,8 @@
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There are some predefined classes deriving from wxLog and which might be
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helpful to see how you can create a new log target class and, of course, may
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also be used without any change. There are:
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@b wxLogStderr This class logs messages to a @e FILE *, using
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stderr by default as its name suggests.
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@b wxLogStream This class has the same functionality as wxLogStderr,
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@@ -155,32 +157,34 @@
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collects all messages generated by the application and also passes them to the
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previous active log target. The log window frame has a menu allowing user to
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clear the log, close it completely or save all messages to file.
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@b wxLogBuffer This target collects all the logged messages in an
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internal buffer allowing to show them later to the user all at once.
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@b wxLogNull The last log class is quite particular: it doesn't do
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anything. The objects of this class may be instantiated to (temporarily)
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suppress output of @e wxLogXXX() functions. As an example, trying to open a
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non-existing file will usually provoke an error message, but if for some
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reasons it is unwanted, just use this construction:
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@code
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wxFile file;
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// wxFile.Open() normally complains if file can't be opened, we don't want it
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{
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wxLogNull logNo;
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if ( !file.Open("bar") )
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... process error ourselves ...
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} // ~wxLogNull called, old log sink restored
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wxLogMessage("..."); // ok
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@endcode
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The log targets can also be combined: for example you may wish to redirect the
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messages somewhere else (for example, to a log file) but also process them as
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normally. For this the #wxLogChain, #wxLogInterposer and
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#wxLogInterposerTemp can be used.
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*/
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