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Careful reordering when adding keyword-only params to a list that already has a variadic keyword. #17
Description
To reproduce:
from i2 import partialx
@partialx(partialx, x=2, _allow_reordering=True)
def foo(x, y, z=0):
return x + y * zleads to:
ValueError: wrong parameter order: variadic keyword parameter before keyword-only parameter
We don't get the problem if we use functools.partial on the external partial:
import functools
@functools.partial(partialx, x=2, _allow_reordering=True)
...
The problem is that we find ourselves in this situation:
[<Parameter "func">, <Parameter "*args">, <Parameter "**kwargs">, <Parameter "__name__=None">, <Parameter "_rm_partialize=False">, <Parameter "_allow_reordering=False">]Hypothesis: Somewhere in the process, the parameters should probably be loosely reordered. We don't want to allow complete reordering, but just enough to allow variadics to be in their proper place (the keyword arguments before the kwargs.
┆Issue is synchronized with this Asana task by Unito
Activity
thorwhalen commentedon Sep 22, 2026
Still reproduces on master (
70125c02), same fundamental error (now raised fromi2.wrapper.move_params_to_the_end->include_exclude->Sig.__getitem__->Sig.from_params, which builds a plaininspect.Signaturefrom reordered params without re-validating/re-sorting variadic-keyword-vs-keyword-only ordering):```python
from i2 import partialx
@partialx(partialx, x=2, _allow_reordering=True)
def foo(x, y, z=0):
return x + y * z
ValueError: wrong parameter order: variadic keyword parameter before keyword-only parameter
```
Root cause looks to be in
i2/wrapper.py::move_params_to_the_end(callsinclude_exclude->include_exclude_ingress_factory->Ingress(inner_sig=sig, outer_sig=sig[include], ...)), wheresig[include]re-orders params but doesn't guarantee the "keyword-only params before**kwargs" invariantinspect.Signaturerequires. Related:Sig.__getitem__/Sig.from_paramsalso silently drops the return annotation on re-indexing (found while fixing #48, #88) -- these two are probably worth fixing together as aSig.__getitem__hardening pass, since several other issues touch the same code path. Leaving as a plan item; not attempting a fix here given the surface area (any change toSig.__getitem__'s reordering affects most of the wrapper/deco module).fix: keep parameter kinds in order when partialx reorders params
fix: keep parameter kinds in order when partialx reorders params
fix: keep parameter kinds in order when partialx reorders params