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Velo uses a hierarchical logging system where each level represents a different severity. The logger discards messages with a level lower than its configured minimum.

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Available log levels

Velo provides seven log levels, defined as Level type in level.go:30-59: 
DebugLevel // -1: Fine grained informational events for debugging

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Level hierarchy

Levels are ordered by severity from lowest to highest. When you set a minimum level, the logger only processes messages at that level or higher:
  • Setting DebugLevel logs everything
  • Setting InfoLevel (default) filters out debug messages
  • Setting ErrorLevel only logs errors and critical messages
PanicLevel causes the logger to panic after writing the message. FatalLevel calls os.Exit(1) after writing, immediately terminating your application.

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Level serialization

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JSON format

The Level.JSONField() method (level.go:65-83) returns a zero-allocation string for JSON serialization: 
{"level":"info"}
{"level":"error"}
{"level":"fatal"}

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Text format

The Level.String() method (level.go:86-105) returns lowercase ASCII representations: 
debug
info
warn
error
dpanic
panic
fatal

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Parsing levels

Velo accepts both lowercase and uppercase level strings via ParseLevel() (level.go:154-158): 
level, err := velo.ParseLevel("info")
level, err := velo.ParseLevel("INFO") // Also valid
The UnmarshalText() method (level.go:118-126) enables configuration via YAML, TOML, or JSON files: 
log_level: error

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Dynamic level adjustment

The AtomicLevel type (level.go:165-167) allows you to safely change log levels at runtime across all goroutines without restarting your application.

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Creating an atomic level

// Initialize at InfoLevel (default)
lvl := velo.NewAtomicLevel()

// Initialize at a specific level
lvl := velo.NewAtomicLevelAt(velo.ErrorLevel)

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Changing levels at runtime

logger := velo.NewWithOptions(os.Stdout, velo.Options{
    Level: lvl.Level(),
})

// Later, increase minimum level to reduce log volume
lvl.SetLevel(velo.ErrorLevel)
The AtomicLevel.SetLevel() method (level.go:209-211) uses atomic operations to ensure thread-safe updates. All loggers referencing the same AtomicLevel immediately respect the new threshold.

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Checking if a level is enabled

if lvl.Enabled(velo.DebugLevel) {
    logger.Debug("detailed diagnostic info")
}
The Enabled() method (level.go:199-201) returns true if the specified level meets or exceeds the current minimum, allowing you to avoid expensive operations when logs would be discarded.

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Special level

Velo internally uses noLevel = 100 (level.go:58) for log entries that should not display a level field. This is an implementation detail not exposed in the public API.

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