Write text as log to a connection

The function writeLog can be used to log outputs and/or running status of scripts to one connection. To use it one does not need to run registerLog first.

writeLog(fmt, ..., con = stdout(), level = 0)

Arguments

fmt

Format string to passed on to sprintf

...

Parameters passed on to sprintf

con

A connection, for instance a file (or its name) or stdout()

level

Logging level: each higher level will add one extra space before the message. See examples

Value

Side effect is used.

Details

In contrast, doLog can be used to log on multiple connections that are registered by registerLog. Therefore, to register logger(s) with registerLog is a prerequisite of calling doLog. Internally doLog calls writeLog sequentially to make multiple-connection logging.

See also

registerLog to register more than one loggers so that doLog can write to them sequentially.

Author

Jitao David Zhang <jitao_david.zhang@roche.com>

Examples

if (FALSE) { # \dontrun{
  writeLog("This is the start of a log")
  writeLog("Message 1", level=1)
  writeLog("Message 1.1", level=2)
  writeLog("Message 1.2", level=2)
  writeLog("Message 2", level=1)
  writeLog("Message 3", level=1)
  writeLog("Message 3 (special)", level=4)
  writeLog("End of the log");
  
  ## log with format
  writeLog("This is Message %d", 1)
  writeLog("Square of 2 is %2.2f", sqrt(2))
  
  ## NA is handled automatically
  writeLog("This is a not available value: %s", NA, level=1)
  writeLog("This is a NULL value: %s", NULL, level=1)
} # }