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--- dev:logging_and_debugging [2014/09/28 08:11] – created ackley
+++ dev:logging_and_debugging [2014/09/28 11:34] (current) – ackley
@@ Line 1: / Line 1: @@
 ====== Logging and Debugging ======
+Here are a few quick notes on getting logging output from the simulator.
+  * The simulator has a logging system accessed via the static object ''LOG''.
+  * The logging system has a 'level' determining how much output is desired.  The level can be set on the command line by the ''-l NUM'' switch, where ''NUM'' can range from 0 to 8.  ''-l 0'' on the command line produces the least output, ''-l 8'' produces the most.
+  * The logging levels have names and numbers: NONE(0), ERROR(1), WARNING(2), MESSAGE(3), DEBUG(4), DEBUG1(5), DEBUG2(6), DEBUG3(7), and ALL(8).
+  * The logging code provides direct methods for producing output at levels ERROR, WARNING, MESSAGE, and DEBUG.  For example: <code cpp>LOG.Debug("Hi there");</code> prints 'Hi there' to the console and the logging buffer (whose display is toggled by 'l' in the GUI) -- **if** the logging level is 4 or larger.
+  * ''LOG'' offers simple, internally-implemented 'printf-like' functionality.  Among other things, it supports '%d', '%o', '%x', '%s'. Its biggest current limitation is no floating point support (so, no '%f', '%e', or '%g' conversions).  For example:
+<code cpp>
+  virtual void Behavior(EventWindow<CC>& window) const
+  {
+    T self = window.GetCenterAtom();
+    LOG.Message("At (%d,%d): type is %04x (%s)",
+                window.GetCenterInTile().GetX(),
+                window.GetCenterInTile().GetY(),
+                self.GetType(),
+                "so there");
+  }
+</code>
+might print something like ''20140928032150-3123: At (14,3): type is 00F0 (so there)''
+if the logging level was 3 or higher.
+  * Note the logger adds a newline at the end of each log message, so typically it's expected that each log message will be a single line.
+  * Use %d for both signed and unsigned ints; there is no '%u'.  (Or use %x or %o).
+  * Grep around in the codebase for 'LOG' to find lots of examples!