log4factorio:

Slim mod for logging inspired by log4j (but with much less functionality 😉).

This is intended as a facility to be used in other mods – it doesn't add any feature to the played game.

Features

Offers the ability to add log statements which can be enabled/disabled by configuration at run time.
It supports the following log levels (AKA severities)

• FATAL
  use for logging severe errors
• ERROR
  use for logging major errors
• WARN
  use for logging minor errors
• INFO
  use for logging informational messages
• CONFIG
  use for logging informational messages concerning configuration
• FINE
  use for logging debug messages
• FINER
  use for logging more verbose debug messages
• FINEST
  use for logging very verbose debug messages

FATAL is the highest, FINEST the lowest log level. Let's say log level is configured to INFO, then only all
loggging calls with a level of INFO or higher (i.e. FATAL, ERROR, WARN and INFO) will be logged, all
others will produce no log entries.

Integration into other mods

1. include it with require

local Log = require("__log4factorio__.Log")

1. set the desired log level, either

   • from configuration

Log.setSeverityFromSettings("testmod1-logLevel")

* or hard coded

Log.setSeverity(Log.WARN)

1. if using configuration add the appropiate entries to the locale files resp. to settings.lua

   ```
   [mod-setting-name]
   testmod1-logLevel=choose log level

   [mod-setting-description]
   testmod1-logLevel=all calls with this log level or higher will be logged (FATAL is the highest, FINEST the lowest level)
   ```

resp.

```
data:extend({
  {
    type = "string-setting",
    name = "testmod1-logLevel",
    order = "zz",
    setting_type = "runtime-global",
    default_value = "CONFIG",
    allowed_values = {
      "FATAL",
      "ERROR",
      "WARN",
      "INFO",
      "CONFIG",
      "FINE",
      "FINER",
      "FINEST",
    }
  },
})
```

For more details please have a look at https://wiki.factorio.com/Tutorial:Mod_settings#Locale

1. Log something

Log.log("sth happened", function(m)log(m)end, Log.INFO)

Log.logLine( { ndx = ndx, wcid = wcid }, function(m)log(m)end, Log.FINE)

Log.logBlock(data, function(m)log(m)end, Log.FINEST)

Assuming that the log level has been set to INFO, that produces entries in factorio-current.log like

137.987 Script @__testMod1__/control.lua:16: [INFO] sth happened

Hints:

1. If you want to log to the factorio-current.log, use function(m)log(m)end instead of simply log. That offers
   the advantage that the logged line number is that from the call in the mod using log4factorio and not the line number
   from inside log4factorio, where log() is executed 😉.

2. Due to the mechanisms of factorio when loading mods, all mods using log4factorio use one shared instance during the
   data phase, so it may (will) come to some interferences if these mods try to set different log levels. The effective log
   level depends on the sequence of loading the mods (and thus is predictable but can't be changed). During the
   control phase each mod has its own instance and thus can set a different log level than the others.