introspect c-functions?

Michael Hudson mwh at
Thu Jun 6 09:33:30 EDT 2002

holger krekel <pyth at> writes:

> is there any way to introspect the *number of arguments*
> of a function implemented at c-level?

In short, no.  To the runtime almost all C functions look roughly like
python functions defined like:

def func(*args):

& so there is no way of telling what the function will do with the
arguments.  There are others -- METH_O and METH_NOARGS style C
functions -- but I don't think you can tell them apart from Python,
and they don't cover all cases.

It's a common, but hardly universal, convention to have the first line
of the docstring be something like

  func(arg1[, arg2]) -> None

so you /might/ be able to dig some info out that way -- but it's
hardly reliable.


  ... but I'd rather not reinvent the wheel if I don't have to.  On
  the other hand, if the currently instantiated version of the wheel
  consists of a square rock covered with moss, I might as well just
  start fresh.                          -- Roy Smith, comp.lang.python

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