Udon has no call stack. A helper handed a string cannot find out who called it, and a world's log is a flat stream from every behaviour at once, so `Debug.Log("done")` is a line nobody can trace back to a file.

Udonite Logging attaches the answer at the call site:

```csharp
using Udonite.Logging;

public class Scoreboard : UdoniteBehaviour
{
    public override void Start()
    {
        Log.Info("ready");
    }

    public void Award(int points)
    {
        Log.Assert(points > 0);

        Log.Info("awarding " + points, "scoring");
    }
}
```

```text
[Scoreboard.Start:7] ready
[assertion failed] [Scoreboard.Award:14] points > 0
[scoring] [Scoreboard.Award:16] awarding -3
```

**It costs nothing.** `[CallerFilePath]`, `[CallerMemberName]` and `[CallerLineNumber]` are substituted by the C# compiler while it binds the call, so by the time a world runs they are constants that were written into the program. There is no lookup, no reflection, and nothing per frame.

## What is in it

| Call | Writes |
|---|---|
| `Log.Info(message)` | an ordinary line |
| `Log.Warning(message)` | a warning |
| `Log.Error(message)` | an error |
| `Log.Assert(condition)` | an error quoting the condition, only when it is false |
| `Log.Entry(message)` | a `LogEntry` object instead of a written line |
| `Log.Site()` | the `[Type.Member:line]` prefix alone |

Every one of them takes an optional tag, which groups related lines without inventing a prefix by hand.

## The Console keeps working after upload

The Unity Console goes blind the moment a world leaves the Editor. After that the only record is a log file with thousands of lines of the client talking to itself.

**Udonite → Open Window → Settings → Logging** reads that file and puts your lines back in the Console, exactly as they read in play mode, so the same window keeps working in a real world with real players in it.

## Where to go next

[Getting started](/docs/logging/getting-started) is the whole of the logging API, and what each part of a line means.

[World logs](/docs/logging/world-logs) is the Editor half: watching a running world from the Console, and what to do when a behaviour faults and switches itself off.