Expand tuple into argument list?

[Michael P. Reilly]

Steven Work <steve at renlabs.com> wrote:
: I'm new to Python.  I want a dispatch function -- takes a function
: name and other arguments, calls the named function with the remaining
: arguments.  This works for limited length argument lists:

: def dispatch(fnname, *rest):
:     fn = dispatch.func_globals[fnname]
:     if len(rest)==0:
:         return fn()
:     elif len(rest)==1:
:         return fn(rest[0])
:     elif len(rest)==2:
:         return fn(rest[0], rest[1])
:     elif len(rest)==3:
:         return fn(rest[0], rest[1], rest[2])
:     elif len(rest)==4:
:         return fn(rest[0], rest[1], rest[2], rest[3])

: but is there a general way to expand the tuple into an argument list?
: (I know about keyword arguments already.)

: Lest you ask why: I'm embedding a Python interpreter in a C program; I 
: need to call Python functions directly from C, and I'd like a single
: point of contact to minimize the required housekeeping.

Inside Python you can replace the if-elif construct with apply:
  def dispatch(fnname, *rest):
    fn = dispatch.func_globals[fnname]
    return apply(fn, rest)

But from C, you will want to use PyObject_CallObject:
  result = PyObject_CallObject(fn, args);
(http://www.python.org/doc/current/api/object.html)

  -Arcege