Logging

Log messages are often very helpful in finding problems.

Logging Information

The log is accessible through the ezLog class. There are multiple functions to log information of different severity:

ezLog::Debug - for verbose output, will be compiled out in non-debug builds
ezLog::Dev - for output during development, will typically be silenced (but not compiled out) in non-development builds
ezLog::Info - for regular information
ezLog::Warning - for important information that may point at problems
ezLog::SeriousWarning - for problems that should be fixed but won't crash the system just now
ezLog::Error - for errors

Log messages can be grouped using the EZ_LOG_BLOCK macro.

TypeScript

Information can also be logged through the TypeScript API.

Inspecting the Log

There are multiple ways to see the content of the log:

In the ezEditor you can open Panels > Log to see two logs, the one for the editor and the one from the engine process.
ezInspector shows the log of the connected process.
The in-game console outputs the log messages.
By default all EZ applications (TODO) also write the log output to a Log.htm file in the application's appdata folder.

Thread-local logging

The logging system uses a thread-local variable to store the active logging system, through which to route all messages that originate on that thread. This can be used to easily replace the entire logging backend on a thread and capture all log messages in a custom backend. See ezLogSystemScope and ezLogInterface, if you want to write a custom backend. This can be used to, for example, capture all output from some subsystem and prevent the messages from reaching the regular outputs.

Custom Log Writers

ezLog is the central class for all messages to be logged. By default, it routes all messages through an instance of ezGlobalLog, though you can redirect this on the calling side if you want. On ezGlobalLog you can register multiple handlers that take the messages and either write them to some output or forward them to another system. This method is used to, for instance, forward log messages from one process to another. The ezInspector integration, for example, registers a custom log writer to gather all log messages, and send them over the network, for display in the external tool. ezEditor does something similar for the messages from the engine process.

For an in-depth explanation of how you can configure the system, see ezLog and ezGlobalLog.