Logging

The jetbrains.mps.baselanguage.logging  language contains statements for writing arbitrary information into the MPS log as well as to the Messages  tool view panel. The  LogLowLevelStatement concept (aka "log error ...") is used for logging using the system logger, while  MsgStatement (aka "message error...") is used for logging into the  Messages tool window.

The Messages tool window is located at the bottom of the screen:

The MPS log file can be quickly navigated to using the menu:

The language supports different severities of log messages:

• trace

• info

• debug

• warn

• error

• fatal

Whenever you want to insert a log statement into code, start by typing either "log" or "message" followed by the desired severity:

Upon completion the log statement with an empty message will be inserted.

The severity level can always be changed:

The log statement also supports exceptions to be specified:

MsgStatement contains an additional parameter to specify the project:

When multiple projects are open in MPS at the same time, each project gets its own MPS windows and thus also its own  Messages view. The  project parameter is used to output the log message into the  Messages window of the right project. If you leave the parameter empty, the message will be logged into Messages tool views of all open projects.