Antoine, Stefan: There doesn't appear to be a bright line separating "this should get a PEP" from "this doesn't need a PEP".  That said, changes to the C API for CPython don't seem to merit PEPs very often, the recent "Stable ABI" being the lone exception to the rule I can recall.  Also, Guido already said (in python-dev) he didn't think it merited a PEP, and I tend to agree.

What I don't understand is what advantage writing a PEP would bring.  If you're worried that it needs discussion--okay, let's discuss it.  Surely we can do that here?  Or in python-dev?  What's on your mind?


Stefan: It sounds like Argument Clinic won't work well for _cdecimal, nor would any alternate DSL grammar work any better, really.  But have no fear--I doubt anyone is going to force you to accept Argument-Clinic-ization of _cdecimal against your will.  If you're comfortable maintaining the _cdecimal code without it, you certainly have my blessing.  Though I do hope you'll add the data needed to generate Signature objects once we figure out what that looks like.


Chris: clinic.txt is available for review as part of the patch I posted, please feel free to make your comments there.  I could file a new patch with the two changes you already suggest if you prefer.  (Though I'm not changing the name of the project to "Parameter Clinic"--the Monty Python reference is simply irresistible.)


Finally, an admission.  I wrote "Argument Clinic" thinking that the inspect.Signature Parameter objects had a per-Parameter docstring.  Well, they don't.  (I feel like an idiot.)  So we could theoretically remove the per-parameter docstrings from the DSL.  However, I'm pretty happy with the current structure of the DSL.  My inclination therefore is to leave them in.  (And who knows, maybe the Parameter object could grow a docstring.)  Still, if you're going to propose changes to the DSL, I submit that removing the per-parameter docstring is wholly viable.