LAPLACE Log (LAPLACE-LHC)

A small, opinionated logging helper built on top of Python’s standard logging module.

laplace_log is designed for multi-module / multi-process scientific or application projects where you want:

• One central logger initialization
• Logs from your app + third‑party libraries
• Clear application names in logs (e.g. laplace.opt)
• Automatic daily log folders
• Simple log.info(...) usage everywhere
• print() statements captured into logs

No external dependencies — just structured, predictable logging.

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Features

• ✅ Root logger configuration (captures library logs)
• ✅ Application‑named logger (app_name)
• ✅ File + console handlers with independent levels
• ✅ Automatic folder structure: logs/YYYY-MM-DD/app_name.log
• ✅ print() and stderr redirection into logs
• ✅ Simple log.info(...) helper available
• ✅ Singleton design (initialize once, use everywhere)
• ✅ Provide an error hook (to avoid silent failures such as PyQt signals)
• ✅ If the logger is not set, the log.example(...) will act as a print(...)

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Installation

Install with pip:

pip install laplace-log

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Quick Start

1. Initialize the logger once (entry point)

from laplace_log import LoggerLHC, log

LoggerLHC(
    app_name="laplace.opt",
    log_root=None,
    file_level="debug",
    console_level="info",
)

log.info("Starting OptWindow...")

2. Use logging anywhere

from laplace_log import log

log.debug("Debug message")
log.info("Information")
log.warning("Something looks odd")
log.error("Something went wrong")

No need to pass logger instances around.

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Log Output Example

2026-01-20 10:21:47 [INFO] [laplace.opt] Starting OptWindow...
2026-01-20 10:21:48 [WARNING] [numpy] overflow encountered in exp
2026-01-20 10:21:49 [INFO] [root] A print statement

• App logs use your app_name
• Library logs keep their original logger names
• print() statements appear as root

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Folder Structure

logs/
└── 2026-01-20/
    └── laplace_opt.log

• A new folder is created each day
• Dots in app_name are replaced by underscores for filenames

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Design Overview

Root logger

The root logger is configured with:

• File handler (persistent logs)
• Console handler (stdout)

This ensures all third‑party libraries are captured automatically.

Application logger

Each app uses its own named logger:

logging.getLogger("laplace.opt")

This name appears in log records and helps identify the source clearly.

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The log Helper

log is a lightweight helper object:

from laplace_log import log
log.info("Hello")

Internally, it forwards calls to the initialized LoggerLHC instance.

If log is used before initialization of LoggerLHC, the message is printed.

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Print Redirection

All print() and sys.stderr output is redirected:

• Printed normally to the console
• Also logged at INFO level via the root logger

This is useful for:

• Legacy code
• Debug prints
• Third‑party libraries using print

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Error Hook

To avoid silent failures, an error hook can be loaded:

from laplace_log import uncaught_exception

This import will by itself make sure that no error will be missed. This is especially useful for PyQt signal errors.

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Configuration Options

LoggerLHC(
    app_name: str,
    log_root: Path | str | None = None,
    file_level: str = "debug",
    console_level: str = "info",
)

Parameter	Description
app_name	Logical name of your application (laplace.opt, lapalce.server, …)
log_root	Base folder for logs (default: current working directory)
file_level	Minimum level written to file
console_level	Minimum level printed to console

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Intended Use Cases

• Scientific applications (optimization, simulations, experiments)
• Multi‑process systems (master / worker / optimizer)
• GUI + backend projects
• Long‑running experiments
• Any project needing clean, centralized logs

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License

GPL-3.0 license