component how-to guide

[atravitz]

resolves #521

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Checklist

• Added a news entry

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• I certify that this contribution is covered by the MIT License here and the Developer Certificate of Origin at https://developercertificate.org/.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.88%. Comparing base (b738422) to head (0b16dcb).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #667   +/-   ##
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  Coverage   98.88%   98.88%           
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  Files          42       42           
  Lines        2685     2685           
=======================================
  Hits         2655     2655           
  Misses         30       30           

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[dotsdl]

Thanks for the improvements to this how-to! I've found several critical technical issues that need fixing before merge. I'm also creating a companion PR with additional enhancements (Overview section, Best Practices, etc.) that you can reference or cherry-pick from.

[dotsdl]

Critical Fix 1: Wrong method names (Line ~90)

CRITICAL: The method names are incorrect. Should be _to_dict() and _from_dict() (with leading underscores), not to_dict() and from_dict().

Current line says:

in this case to_dict() and from_dict().

These are the actual private method names that need to be implemented for serialization. If users follow this as written, their code won't work.

Suggested fix:

In other cases, such as when inheriting from ``ExplicitMoleculeComponent``, you will only need to define methods specifically not implemented - in this case ``_to_dict()`` and ``_from_dict()``.

[dotsdl]

Critical Fix 2: Missing imports (Line ~45)

CRITICAL: The first test example is missing required imports. As written, this code won't run because GufeTokenizableTestsMixin, pytest, and Chem are not imported but are used in the code.

Current code is missing these imports:

from gufe.tests import GufeTokenizableTestsMixin
import pytest
from rdkit import Chem

Suggested fix: Add all imports at the top of the test file example in Step 2.

[dotsdl]

Critical Fix 3: Missing serialization warning (After Step 4 example)

CRITICAL: Need to warn users that adding custom attributes (like custom_attribute in the Step 4 example) requires implementing _to_dict(), _from_dict(), and _gufe_tokenize() methods. Without this warning, users will create components that fail to serialize/deserialize correctly.

Suggested addition after the print_custom_attribute method example:

.. warning::
   If you add custom attributes like ``custom_attribute`` above, you must also implement
   ``_to_dict()``, ``_from_dict()``, and ``_gufe_tokenize()`` methods to properly handle
   serialization and hashing. See the :ref:`serialization how-to <howto-serialization>`
   for details. The example above is simplified to demonstrate adding methods; in practice,
   you may want to add only methods (not attributes) to avoid serialization complexity.

[dotsdl]

Critical Fix 4: Broken Sphinx reference (Line 6)

The Sphinx reference syntax is malformed - missing space in :ref:\Component`andGufeTokenizable` isn't cross-referenced at all.

Current:

The **gufe**  :ref:`Component<component>` is a GufeTokenizable intended to be used...

Should be:

The **gufe**  :ref:`Component <component>` is a :ref:`GufeTokenizable <understanding_gufetokenizables>` intended to be used as an *extensible point* of the library, so that you can describe a simulated system in terms of ``GufeTokenizable``\s that are compatible with **gufe** and the rest of the OpenFE ecosystem.

This ensures proper cross-linking in the rendered documentation.

[dotsdl]

Critical Fix 5: Missing news entry

PR checklist requires a news entry but none exists. Please create news/component-howto.rst:

**Added:**

* Added how-to guide for defining custom ``Component`` subclasses, covering extensible base classes, required methods, testing strategies, and serialization considerations.

**Changed:**

* <news item>

**Deprecated:**

* <news item>

**Removed:**

* <news item>

**Fixed:**

* <news item>

**Security:**

* <news item>

[IAlibay]

Couple of comments / nits, otherwise it looks good to me.

[github-actions]

No API break detected ✅