docs/latex/wx/log.tex

   1 \section{\class{wxLog}}\label{wxlog}
   2
   3 wxLog class defines the interface for the {\it log targets} used by wxWindows
   4 logging functions as explained in the \helpref{wxLog overview}{wxlogoverview}.
   5 The only situations when you need to directly use this class is when you want
   6 to derive your own log target because the existing ones don't satisfy your
   7 needs. Another case is if you wish to customize the behaviour of the standard
   8 logging classes (all of which respect the wxLog settings): for example, set
   9 which trace messages are logged and which are not or change (or even remove
  10 completely) the timestamp on the messages.
  11
  12 Otherwise, it is completely hidden behind the {\it wxLogXXX()} functions and
  13 you may not even know about its existence.
  14
  15 See \helpref{log overview}{wxlogoverview} for the descriptions of wxWindows
  16 logging facilities.
  17
  18 \wxheading{Derived from}
  19
  20 No base class
  21
  22 \latexignore{\rtfignore{\wxheading{Function groups}}}
  23
  24 \membersection{Static functions}
  25
  26 The functions in this section work with and manipulate the active log target.
  27 The {\it OnLog()} is called by the {\it wxLogXXX()} functions and invokes the
  28 {\it DoLog()} of the active log target if any. Get/Set methods are used to
  29 install/query the current active target and, finally, {\it
  30 DontCreateOnDemand()} disables the automatic creation of a standard log target
  31 if none actually exists. It is only useful when the application is terminating
  32 and shouldn't be used in other situations because it may easily lead to a loss
  33 of messages.
  34
  35 \helpref{OnLog}{wxlogonlog}\\
  36 \helpref{GetActiveTarget}{wxloggetactivetarget}\\
  37 \helpref{SetActiveTarget}{wxsetactivetarget}\\
  38 \helpref{DontCreateOnDemand}{wxlogdontcreateondemand}
  39
  40 \membersection{Message buffering}
  41
  42 Some of wxLog implementations, most notably the standard
  43 \helpref{wxLogGui}{wxloggui} class, buffer the messages (for example, to avoid
  44 showing the user a zillion of modal message boxes one after another - which
  45 would be really annoying). {\it Flush()} shows them all and clears the buffer
  46 contents. Although this function doesn't do anything if the buffer is already
  47 empty, {\it HasPendingMessages()} is also provided which allows to explicitly
  48 verify it.
  49
  50 \helpref{Flush}{wxlogflush}\\
  51 \helpref{HasPendingMessages}{haspendingmessages}
  52
  53 \membersection{Customization}{wxlogcustomization}
  54
  55 The functions below allow some limited customization of wxLog behaviour
  56 without writing a new log target class (which, aside of being a matter of
  57 several minutes, allows you to do anything you want).
  58
  59 The verbose messages are the trace messages which are not disabled in the
  60 release mode and are generated by {\it wxLogVerbose()}. They are not normally
  61 shown to the user because they present little interest, but may be activated,
  62 for example, in order to help the user find some program problem.
  63
  64 As for the (real) trace messages, they come in different kinds:
  65 \begin{itemize}\itemsep=0pt
  66 \item{wxTraceMemAlloc} for the messages about creating and deleting objects
  67 \item{wxTraceMessages} for tracing the windowing system messages/events
  68 \item{wxTraceResAlloc} for allocating and releasing the system ressources
  69 \item{wxTraceRefCount} for reference counting related messages
  70 \item{wxTraceOleCalls} for the OLE (or COM) method invocations (wxMSW only)
  71 \item{other} the remaining bits are free for user-defined trace levels
  72 \end{itemize}
  73
  74 The trace mask is a bit mask which tells which (if any) of these trace
  75 messages are going to be actually logged. For the trace message to appear
  76 somewhere, all the bits in the mask used in the call to {\it wxLogTrace()}
  77 function must be set in the current trace mask. For example,
  78 \begin{verbatim}
  79 wxLogTrace(wxTraceRefCount | wxTraceOle, "Active object ref count: %d", nRef);
  80 \end{verbatim}
  81 will do something only if the current trace mask contains both wxTraceRefCount
  82 and wxTraceOle.
  83
  84 Finally, the {\it wxLog::DoLog()} function automatically prepends a time stamp
  85 to all the messages. The format of the time stamp may be changed: it can be
  86 any string with \% specificators fully described in the documentation of the
  87 standard {\it strftime()} function. For example, the default format is
  88 "[\%d/\%b/\%y \%H:\%M:\%S] " which gives something like "[17/Sep/98 22:10:16] "
  89 (without quotes) for the current date. Setting an empty string as the time
  90 format disables timestamping of the messages completely.
  91
  92 \helpref{SetVerbose}{wxlogsetverbose}\\
  93 \helpref{GetVerbose}{wxloggetverbose}\\
  94 \helpref{SetTimeStampFormat}{wxlogsettimestampformat}\\
  95 \helpref{GetTimeStampFormat}{wxloggettimestampformat}\\
  96 \helpref{SetTraceMask}{wxlogsettracemask}\\
  97 \helpref{GetTraceMask}{wxloggettracemask}
  98
  99 %%%%% MEMBERS HERE %%%%%
 100 \helponly{\insertatlevel{2}{
 101
 102 \wxheading{Members}
 103
 104 }}
 105
 106 \membersection{wxLog::OnLog}\label{wxlogonlog}
 107
 108 \func{static void}{OnLog}{\param{wxLogLevel }{ level}, \param{const char * }{ message}}
 109
 110 Forwards the message at specified level to the {\it DoLog()} function of the
 111 active log target if there is any, does nothing otherwise.
 112
 113 \membersection{wxLog::GetActiveTarget}\label{wxloggetactivetarget}
 114
 115 \func{static wxLog *}{GetActiveTarget}{\void}
 116
 117 Returns the pointer to the active log target (may be NULL).
 118
 119 \membersection{wxLog::SetActiveTarget}\label{wxlogsetactivetarget}
 120
 121 \func{static wxLog *}{SetActiveTarget}{\param{wxLog * }{ logtarget}}
 122
 123 Sets the specified log target as the active one. Returns the pointer to the
 124 previous active log target (may be NULL).
 125
 126 \membersection{wxLog::DontCreateOnDemand}\label{wxlogdontcreateondemand}
 127
 128 \func{static void}{DontCreateOnDemand}{\void}
 129
 130 Instructs wxLog to not create new log targets on the fly if there is none
 131 currently. (Almost) for internal use only.
 132
 133 \membersection{wxLog::Flush}{wxlogflush}
 134
 135 \func{virtual void}{Flush}{\void}
 136
 137 Shows all the messages currently in buffer and clears it. If the buffer
 138 is already empty, nothing happens.
 139
 140 \membersection{wxLog::HasPendingMessages}{haspendingmessages}
 141
 142 \constfunc{bool}{HasPendingMessages}{\void}
 143
 144 Returns true if there are any messages in the buffer (not yet shown to the
 145 user). (Almost) for internal use only.
 146
 147 \membersection{wxLog::SetVerbose}{wxlogsetverbose}
 148
 149 \func{void}{SetVerbose}{\param{bool }{ verbose = TRUE}}
 150
 151 Activates or desactivates verbose mode in which the verbose messages are
 152 logged as the normal ones instead of being silently dropped.
 153
 154 \membersection{wxLog::GetVerbose}{wxloggetverbose}
 155
 156 \constfunc{bool}{GetVerbose}{\void}
 157
 158 Returns whether the verbose mode is currently active.
 159
 160 \membersection{wxLog::SetTimeStampFormat}{wxlogsettimestampformat}
 161
 162 \func{void}{SetTimeStampFormat}{\param{const char * }{ format}}
 163
 164 Sets the timestamp format prepended by the default log targets to all
 165 messages. The string may contain any normal characters as well as \%
 166 prefixed format specificators, see {\it strftime()} manual for details.
 167 Passing an empty string to this function disables message timestamping.
 168
 169 \membersection{wxLog::GetTimeStampFormat}{wxloggettimestampformat}
 170
 171 \constfunc{const char *}{GetTimeStampFormat}{\void}
 172
 173 Returns the current timestamp format string.
 174
 175 \membersection{wxLog::SetTraceMask}{wxlogsettracemask}
 176
 177 \func{static void}{SetTraceMask}{\param{wxTraceMask }{ mask}}
 178
 179 Sets the trace mask, see \helpref{Customization}{wxlogcustomization}
 180 section for details.
 181
 182 \membersection{wxLog::GetTraceMask}{wxloggettracemask}
 183
 184 Returns the current trace mask, see \helpref{Customization}{wxlogcustomization}
 185 section for details.