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While working on#103553 I found one more problem that merits its own issue.
Right now it is impossible to create a function that have a pos-or-keyword parameter without a default comming after a pos-only parameter with a default. Demo:
>>>deftest(pod=42,/,pk): ...File"<stdin>",line1deftest(pod=42,/,pk): ...^^SyntaxError:parameterwithoutadefaultfollowsparameterwithadefault>>>lambdapod=42,/,pk: ...File"<stdin>",line1lambdapod=42,/,pk: ...^^SyntaxError:parameterwithoutadefaultfollowsparameterwithadefault
But, it is possible to create a signature like this. Repro:
>>>importinspect>>>defone(pk): ......>>>deftwo(pod=42,/): ......>>>sig1=inspect.signature(one)>>>sig2=inspect.signature(two)>>>inspect.Signature((sig2.parameters['pod'],sig1.parameters['pk']))<Signature (pod=42,/,pk)>
This looks like a bug to me, there's no reason for a signature to behave differently and to support function signatures that cannot be created.
Desired behaviour:
Traceback (mostrecentcalllast):File"/Users/sobolev/Desktop/cpython/ex.py",line7,in<module>print(inspect.Signature((sig2.parameters['pod'],sig1.parameters['pk'])))^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^File"/Users/sobolev/Desktop/cpython/Lib/inspect.py",line3039,in__init__raiseValueError(msg)ValueError:non-defaultargumentfollowsdefaultargument
The fix is quite easy. PR is incomming.
I've also tried the same thing with#103404 (because it is very related) but, it still does not solve this corner case.