Replace deprecated serial_handler imports with pslab.connection

[Architrb1795]

Fixes #271

Summary

This PR migrates usage of the deprecated pslab.serial_handler module to the modern pslab.connection.SerialHandler API and updates the CLI to explicitly manage the connection lifecycle.

Motivation

The pslab.serial_handler module is deprecated and emits warnings duringdocumentation builds and runtime.

While migrating to pslab.connection.SerialHandler, a behavioral difference was identified: the new API does not auto-connect on initialization, whereas the deprecated implementation did.

This caused the CLI (pslab/cli.py) to rely on implicit behavior that no longer exists, potentially leading to runtime failures.

Changes Made

• Replaced deprecated pslab.serial_handler imports with
  pslab.connection.SerialHandler in:
  • pslab/cli.py
  • pslab/external/gas_sensor.py
  • pslab/external/hcsr04.py
  • pslab/external/tcd1304.py
• Updated CLI initialization logic to:
  • Explicitly call handler.connect()
  • Ensure handler.disconnect() is always called via a safe lifecycle
• Updated internal documentation to reference the new API

Verification

• tox -e docs (deprecation warning removed)
• tox -e lint (clean)
• CLI connection tested with both explicit port selection and auto-detection

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

This PR replaces deprecated pslab.serial_handler imports with the modern pslab.connection.SerialHandler and updates internal docs to reference the new module, eliminating deprecation warnings during docs builds.

File-Level Changes

Change	Details	Files
Swap all SerialHandler imports from the deprecated serial_handler module to the supported connection module.	Update CLI module to import SerialHandler from pslab.connection Update external gas sensor helper to import SerialHandler from pslab.connection Update external HCSR04 helper to import SerialHandler from pslab.connection Update external TCD1304 helper to import SerialHandler from pslab.connection	pslab/cli.py pslab/external/gas_sensor.py pslab/external/hcsr04.py pslab/external/tcd1304.py
Align internal documentation with the new SerialHandler import path.	Replace references to pslab.serial_handler with pslab.connection in internal documentation	docs/internal.rst

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[Architrb1795]

Hi maintainers,
This is a small cleanup PR to remove usage of a deprecated module and reduce docs build warnings.
Happy to make any changes if needed, thanks for reviewing!

[Copilot]

Pull request overview

This PR updates the codebase to stop importing the deprecated pslab.serial_handler module (which emits a deprecation warning during docs builds) and instead use the modern pslab.connection API.

Changes:

• Switched SerialHandler imports from pslab.serial_handler to pslab.connection in the CLI and external sensor drivers.
• Updated internal documentation to reference pslab.connection instead of the deprecated module.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
pslab/cli.py	Updates SerialHandler import to pslab.connection.
pslab/external/gas_sensor.py	Updates SerialHandler import to pslab.connection.
pslab/external/hcsr04.py	Updates SerialHandler import to pslab.connection.
pslab/external/tcd1304.py	Updates SerialHandler import to pslab.connection.
docs/internal.rst	Updates autodoc target module to pslab.connection to avoid deprecated import warnings.

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[Copilot]

pslab.connection.SerialHandler has different runtime behavior than the deprecated pslab.serial_handler.SerialHandler: it requires an explicit port (no implicit autoconnect when args.port is None) and it does not auto-connect() in __init__. In main() this file currently does handler = SerialHandler(port=args.port) and then uses it without calling handler.connect(), which will leave the serial port closed (and may also pass None as the port). Update CLI initialization to use autoconnect() when no port is provided and/or call handler.connect() before use (and ensure disconnect() in a finally).

Suggested change

	from pslab.connection import SerialHandler
	from pslab.serial_handler import SerialHandler

[mariobehling]

Thanks for the PR. Cleaning up the deprecated pslab.serial_handler imports is a good direction, and the change set is nicely small.

However, this is not a pure warning cleanup. pslab.connection.SerialHandler can behave differently than the deprecated handler, and in pslab/cli.py the code currently creates the handler and uses it without an explicit connect(), while args.port may be None. That can leave the port closed or fail at runtime.

Please do the following before we can merge:

1. Open an issue describing the deprecation cleanup and the expected runtime behaviour of the CLI, then link it in the PR description using GitHub best practice: Fixes #<issue-number>.

2. Add a short screencast showing this working on your machine:

   • tox -e docs with the warning removed
   • running the CLI command you tested, showing it successfully connects (include the exact command and whether a port is provided or auto detected)

3. Update the CLI initialization to match the intended pslab.connection.SerialHandler usage, for example call connect() explicitly or use the proper auto connect flow, and ensure clean disconnect in a safe way.

Once the CLI behaviour is verified and captured in the issue and screencast, this becomes a clean and mergeable deprecation removal.

[mariobehling]

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[Architrb1795]

https://drive.google.com/file/d/1GLzB5s8oU4dDxOSFgL_CdgA9FAJZAwgg/view?usp=sharing

Thanks for the review!

I’ve updated the CLI to explicitly manage the connection lifecycle when migrating to pslab.connection.SerialHandler, and linked the related issue (Fixes #271).

I’ve also attached a short screencast demonstrating:

• tox -e docs running without the deprecation warning
• Successful CLI execution
• Graceful failure with an invalid port

Please let me know if any further adjustments are needed.