Python: Use multi-phase initialisation (PEP 489)
#21,995 opened on May 28, 2025
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Description
What language does this apply to?
Python
Describe the solution you'd like
Hello,
Please consider adopting multi-phase init for your Python extension modules. In short, multi-phase makes extension modules behave more like pure-Python modules and means that the import system can determine what a module supports before executing it.
Multi-phase initialisation was introduced in PEP 489 for Python 3.5. It replaces the previous 'single-phase' mechanism by splitting the module creation process into creation and execution phases. Quoting from the documentation:
Extension modules created this way behave more like Python modules: the initialization is split between the creation phase, when the module object is created, and the execution phase, when it is populated. The distinction is similar to the
__new__()and__init__()methods of classes.
It is the preferred mechanism for extension module initialisation, and we are considering explicitly deprecating single phase init.
Describe alternatives you've considered
The status quo.
A