[Python-Dev] Calling a builtin from C code; PEP 3101 format() builtin

[Georg Brandl]

Eric Smith schrieb:
> While implementing "".format(), I need to call the builtin format()
> function, which I've already implemented (in
> bltinmodule.c:builtin_format()).  In the py3k branch, I just hardcoded
> the same functionality into "".format(), which seems like the wrong 
> thing to do, given how complex the code is.
> 
> I see 2 approaches:
> 
> 1: exposing builtin_format(), probably giving it another name 
> (PyObject_Format?) and moving it somewhere other than bltinmodule.c.
> 
> 2: Instead of calling the C code directly, lookup "format" in Python's
> builtins, and call it.  This, I think, would allow you to override the
> global format() function if you wanted to modify the behavior (although
> I can't think of any use case for wanting to do that).
> 
> I don't see where either behavior is specified in the PEP.
> 
> If option 2 is preferred, could someone give me a pointer to how to find 
> a builtin function from C code?

I don't know which option Guido prefers, but for looking up a function
from the builtins, look at Python/import.c:PyImport_Import which does
this with __import__.

Georg


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