SNekLog/RELEASE_NOTES.md

v2.0.0

Highlights

• Renamed the public Go package from slog to sneklog to avoid confusion with the standard library log/slog package.
• Moved the module path to git.scuroneko.dev/scuroneko/slog/v2 for Go module major-version compatibility.
• Replaced fixed text writer settings with formatter-based output customization.
• Added built-in ANSI color support and removed the external github.com/fatih/color dependency tree.
• Formatters: a new way do display your logs!

Breaking Changes

• Import paths must use the /v2 module suffix:

import sneklog "git.scuroneko.dev/scuroneko/slog/v2"

• Package references should use sneklog instead of slog.
• Removed Logger.PrintTime and Logger.PrintTraceback; configure output through writer formatters instead.
• Changed text writer constructors:
  • CreateTextWriter(w, printTraceback, printTime) is now CreateTextWriter(w).
  • CreateTextFileWriter(path, printTraceback, printTime) is now CreateTextFileWriter(path).
  • CreateTextStdoutWriter(printTraceback, printTime) is now CreateTextStdoutWriter().
• Removed the old text formatting helpers: BuildString, FormatTime, FormatTraceback, and FormatFullTraceback.
• JSON time values are now formatted through the configured formatter and stored as strings in LoggerJsonMessage.

Added

• Formatter for configurable message layouts, timestamp layouts, traceback layouts, separators, and color behavior.
• DefaultTextFormatter and DefaultJsonFormatter defaults for text and JSON writers.
• LoggerTextWriter.SetFormatter and LoggerJsonWriter.SetFormatter.
• Strftime-like timestamp format constants such as RFC3339, Kitchen, DateTime, DateOnly, and TimeOnly.
• Built-in color types and helpers:
  • FgColor, BgColor, and Attribute.
  • ColorStringBuilder.
  • Level color getters/setters on LogLevel.
• Tests covering formatter defaults, empty traceback placeholders, literal % sequences in messages, color controls, and JSON newline semantics.

Changed

• Text output defaults to DefaultTextFormatter instead of the old hard-coded string builder.
• JSON output defaults to DefaultJsonFormatter and can now format the JSON message field through Formatter.
• Newline semantics are normalized before text and JSON formatting, so trailing \n controls record termination without becoming part of the message.
• Text color output is enabled by default only for stdout/stderr.
• Example code now demonstrates custom formatters and color configuration.
• Go dependencies were simplified by removing:
  • github.com/fatih/color
  • github.com/mattn/go-colorable
  • github.com/mattn/go-isatty
  • golang.org/x/sys

Fixed

• NewFormatter() now returns a fresh copy instead of mutating DefaultTextFormatter.
• Formatter.FormatMessage no longer panics when called with an empty traceback.
• Placeholder-looking text inside log messages, such as %L or %s, is preserved literally.
• SetColorOutput(false) disables color output.
• SetColorOnlyStdout(false) allows color output for non-stdout writers.

Migration

Before:

import "git.scuroneko.dev/scuroneko/slog"

logger := slog.CreateLogger().
	Prefix("API").
	Level(slog.DEBUG).
	PrintTraceback(true)

text := logger.CreateTextStdoutWriter()

After:

import sneklog "git.scuroneko.dev/scuroneko/slog/v2"

logger := sneklog.CreateLogger().
	Prefix("API").
	Level(sneklog.DEBUG)

formatter := sneklog.NewFormatter().
	SetFormat("%t [%L] %N: %m (%B)")

text := logger.CreateTextStdoutWriter().
	SetFormatter(formatter)

v1.2.0

Highlights

• Added message replacement with Logger.AddReplacer(old, new) for masking secrets or normalizing log output.
• Preserved the existing LoggerWriter.Print(...any) contract, so custom writers do not need a signature update.
• Improved JSON writer newline handling for messages that already end with \n.

Added

• Logger.AddReplacer(old, new) appends a replacement rule that is applied before records are sent to writers.
• README and package GoDoc now document message replacement and include usage examples.
• Tests covering message type preservation for custom writers, JSON empty messages, and JSON trailing newline behavior.

Fixed

• LoggerJsonWriter.Print no longer panics when called with no message arguments.
• LoggerJsonWriter.Print now treats a trailing newline at the end of the last message as newline semantics and does not include that newline in the JSON message field.
• Log messages keep their original argument types for custom writers when no replacement rules are configured.

Changed

• Updated the example program to demonstrate AddReplacer.
• Updated dependencies:
  • github.com/fatih/color from v1.18.0 to v1.19.0
  • github.com/mattn/go-isatty from v0.0.20 to v0.0.21
  • golang.org/x/sys from v0.42.0 to v0.43.0

Compatibility

No breaking API changes are intended in this release. The public LoggerWriter interface continues to accept messages ...any.