added devel/logging; weakrefs test; next steps for proper unsigned support

devel/logging.nim

@@ -0,0 +1,145 @@
+#
+#
+#            Nimrod's Runtime Library
+#        (c) Copyright 2012 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## This module implements a simple logger. It is based on the following design:
+## * Runtime log formating is a bug: Sooner or later every log file is parsed.
+## * Keep it simple: If this library does not fullfill your needs, write your 
+##   own. Trying to support every logging feature just leads to bloat.
+## 
+## Format is:: 
+##
+##   DEBUG|INFO|... (2009-11-02 00:00:00)? (Component: )? Message
+##
+## 
+
+type
+  TLevel* = enum  ## logging level
+    lvlAll,       ## all levels active
+    lvlDebug,     ## debug level (and any above) active
+    lvlInfo,      ## info level (and any above) active
+    lvlWarn,      ## warn level (and any above) active
+    lvlError,     ## error level (and any above) active
+    lvlFatal      ## fatal level (and any above) active
+
+const
+  LevelNames*: array [TLevel, string] = [
+    "DEBUG", "DEBUG", "INFO", "WARN", "ERROR", "FATAL"
+  ]
+
+type
+  TLogger* = object of TObject ## abstract logger; the base type of all loggers
+    levelThreshold*: TLevel    ## only messages of level >= levelThreshold 
+                               ## should be processed
+  TConsoleLogger* = object of TLogger ## logger that writes the messages to the
+                                      ## console
+  
+  TFileLogger* = object of TLogger ## logger that writes the messages to a file
+    f: TFile
+    
+  TRollingFileLogger* = object of TFileLogger ## logger that writes the 
+                                              ## message to a file
+    maxlines: int # maximum number of lines
+    lines: seq[string]
+
+method log*(L: ref TLogger, level: TLevel,
+            frmt: string, args: openArray[string]) =
+  ## override this method in custom loggers. Default implementation does
+  ## nothing.
+  nil
+  
+method log*(L: ref TConsoleLogger, level: TLevel,
+            frmt: string, args: openArray[string]) = 
+  Writeln(stdout, LevelNames[level], " ", frmt % args)
+
+method log*(L: ref TFileLogger, level: TLevel, 
+            frmt: string, args: openArray[string]) = 
+  Writeln(L.f, LevelNames[level], " ", frmt % args)
+
+proc defaultFilename*(): string = 
+  ## returns the default filename for a logger
+  var (path, name, ext) = splitFile(getAppFilename())
+  result = changeFileExt(path / name & "_" & getDateStr(), "log")
+
+proc substituteLog*(frmt: string): string = 
+  ## converts $date to the current date
+  ## converts $time to the current time
+  ## converts $app to getAppFilename()
+  ## converts 
+  result = newStringOfCap(frmt.len + 20)
+  var i = 0
+  while i < frmt.len: 
+    if frmt[i] != '$': 
+      result.add(frmt[i])
+      inc(i)
+    else:
+      inc(i)
+      var v = ""
+      var app = getAppFilename()
+      while frmt[i] in IdentChars: 
+        v.add(toLower(frmt[i]))
+        inc(i)
+      case v
+      of "date": result.add(getDateStr())
+      of "time": result.add(getClockStr())
+      of "app":  result.add(app)
+      of "appdir": result.add(app.splitFile.dir)
+      of "appname": result.add(app.splitFile.name)
+      
+
+proc newFileLogger*(filename = defaultFilename(), 
+                    mode: TFileMode = fmAppend,
+                    levelThreshold = lvlNone): ref TFileLogger = 
+  new(result)
+  result.levelThreshold = levelThreshold
+  result.f = open(filename, mode)
+
+proc newRollingFileLogger*(filename = defaultFilename(), 
+                           mode: TFileMode = fmAppend,
+                           levelThreshold = lvlNone,
+                           maxLines = 1000): ref TFileLogger = 
+  new(result)
+  result.levelThreshold = levelThreshold
+  result.maxLines = maxLines
+  result.f = open(filename, mode)
+
+var
+  level* = lvlNone
+  handlers*: seq[ref TLogger] = @[]
+
+proc logLoop(level: TLevel, msg: string) =
+  for logger in items(handlers): 
+    if level >= logger.levelThreshold:
+      log(logger, level, msg)
+
+template log*(level: TLevel, msg: string) =
+  ## logs a message of the given level
+  bind logLoop
+  if level >= logging.Level:
+    logLoop(level, frmt, args)
+
+template debug*(msg: string) =
+  ## logs a debug message
+  log(lvlDebug, msg)
+
+template info*(msg: string) = 
+  ## logs an info message
+  log(lvlInfo, msg)
+
+template warn*(msg: string) = 
+  ## logs a warning message
+  log(lvlWarn, msg)
+
+template error*(msg: string) = 
+  ## logs an error message
+  log(lvlError, msg)
+  
+template fatal*(msg: string) =  
+  ## logs a fatal error message
+  log(lvlFatal, msg)
+