I would like to propose allowing runtime access to arguments of type application (parameters) on classes inside of classmethods and the __init__
function.
I originally brought this up on the thread for implementing PEP 585, because it might entail changes to the runtime data structure being created there, but was advised that this would have to be brought up separately and would likely result in it's own PEP if there is expressed desire for it and a reasonable way to implement it (https://mail.python.org/archives/list/typing-sig@python.org/message/TQQRXNXY5KU2BG3Y7LPVN4QOSTRZZ2L6/).
This would allow a common syntax to create strongly typed collections to be analyzed by tools like MyPy and also used at runtime. Many built in collections do not need this feature, because at runtime they can be heterogeneous.