Source-generated logging

XenoAtom.Logging includes source generators and analyzers embedded in the core package.

This generator covers two features:

[LogMethod]: generates strongly-typed logging methods from message templates.
[LogFormatter]: generates high-performance text formatters from declarative templates.

Attribute-based API

Declare static partial methods with [LogMethod]:

using XenoAtom.Logging;

public static partial class AppLogs
{
    [LogMethod(LogLevel.Info, "User {userId} connected from {ip}")]
    public static partial void UserConnected(Logger logger, int userId, string ip);

    [LogMethod(LogLevel.Error, "Request {requestId} failed", EventId = 42, EventName = "RequestFailed")]
    public static partial void RequestFailed(Logger logger, Exception exception, LogProperties properties, int requestId);
}

The generator emits method implementations that:

perform a level check (logger.IsEnabled(level))
construct optional LogEventId
call the matching generated LoggerExtensions level method
emit interpolation code derived from the compile-time template

Message template rules

Placeholder syntax: {name}, {name,alignment}, {name:format}, {name,alignment:format}
Escaped braces: write two opening braces ({ then {) or two closing braces (} then }).
Placeholder names must match method parameter names (case-insensitive)

Analyzer diagnostics

XLG0100: placeholder parameter type may allocate during generated logging.
- Preferred types: string, bool, unmanaged ISpanFormattable values.

Generator diagnostics

XLG0001: invalid [LogMethod] signature
XLG0002: unsupported log level
XLG0003: invalid message template
XLG0004: unknown template parameter

Log formatters

To create custom text formatters, use [LogFormatter] on a partial record inheriting LogFormatter:

using XenoAtom.Logging;

[LogFormatter("{Timestamp:HH:mm:ss} {Level,-5} {LoggerName} {Text}{? | {Exception}?}")]
public sealed partial record MyFormatter : LogFormatter;

See Log Formatters for usage, template quick reference, and generator setup guidance.