PEP 741: Add Multi-phase section (#3706)

Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>

peps/pep-0741.rst

@@ -1053,6 +1053,36 @@ implemented in Python 3.8.
 Disallow setting the ``"configure_locale"`` option has similar issues.
 
 
+Multi-phase initialization (similar to PEP 432)
+-----------------------------------------------
+
+`Eric Snow expressed concerns <https://discuss.python.org/t/pep-741-python-configuration-c-api-second-version/45403/27>`_
+that this proposal might reinforce with embedders the idea that
+initialization is a single monolithic step.  He argued that initialization
+involves 5 distinct phases and even suggested that the API should
+reflect this explicitly.  Eric proposed that, at the very least, the
+implementation of initialization should reflect the phases, in part
+for improved code health.  Overall, his explanation has some
+similarities with :pep:`432` and :pep:`587`.
+
+Another of Eric's key points relevant to this PEP was that, ideally,
+the config passed to ``Py_InitializeFromConfig()`` should be complete
+before that function is called, whereas currently initialization
+actually modifies the config.
+
+While Eric wasn't necessarily suggesting an alternative to PEP 741,
+any proposal to add a granular initialization API around phases is
+effectively the opposite of what this PEP is trying to accomplish.
+Such API is more complicated, it requires adding new public structures
+and new public functions. It makes the Python initialization more
+complicated, rather than this PEP tries to unifiy existing APIs and make
+them simpler (the opposite). Having multiple structures for similar
+purpose can lead to duplicate members, similar issue than duplicated
+members between existing ``PyPreConfig`` and ``PyConfig`` structures.
+
+.. XXX Are the concerns still valid about the config currently not
+   being complete before ``Py_InitializeFromConfig()`` is called?
+
 
 Discussions
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