[C++-sig] functions not showing up in pydoc

[Ralf W. Grosse-Kunstleve]

--- Nick Rasmussen <nick at ilm.com> wrote:

> I'm running into a problem with functions at the module level not
> showing up in pydoc.  The problem is that the type of the function
> object in the module is:
> 
> >>> type(testfoo.foo)
> <type 'Boost.Python.function'>
> 
> Which isn't a sublcass of <type 'builtin_function_or_method'>
> 
> When pydoc walks the module it only documents routines that are
> either builtin (according to inspect.isbuiltin) or are objects
> whose module can be deduced via inspect.getmodule.
> 
> I modified function.cpp with:
> 
> --- libs/python/src/object/function.cpp.orig    2005-02-07 17:11:52.000066304
> -0800
> +++ libs/python/src/object/function.cpp 2005-02-07 16:55:24.000120507 -0800
> @@ -608,7 +608,7 @@
>      0,                                  /* tp_methods */
>      0, // func_memberlist,              /* tp_members */
>      function_getsetlist,                /* tp_getset */
> -    0,                                  /* tp_base */
> +    &PyCFunction_Type,                  /* tp_base */
>      0,                                  /* tp_dict */
>      function_descr_get,                 /* tp_descr_get */
>      0,                                  /* tp_descr_set */
> 
> and it seemed to fix it.  Is this right, or is there a different
> way that functions should get exposed such that pydoc can understand
> them?

I applied this patch locally and tested it in 14 different configurations. It
appears to work OK with Python 2.2, but leads to platform-specific fatal errors
with Python 2.3 and 2.4 (Abort, Bus error, C assertions in Python, or plain
wrong results). Here is the full damage:

http://cci.lbl.gov/cctbx_build/show_error_summary.cgi?build_tag=2005_02_10_1102

(This page will go away after a few days.)

Using the exact same sources, but without the patch above, eliminates all
errors.

Before I knew about the Python 2.3 and 2.4 failures I asked David Abrahams
regarding the patch. For the records:

> > With regards to this posting:
> >
> >   http://mail.python.org/pipermail/c++-sig/2005-February/008541.html
> >
> > I've applied the patch locally. All the tests run fine.
> > Can you think of any negative side-effects of applying the patch?
> 
> Well, I think it's probably benign.
> 
> It might mean that BPL function objects get bigger.  Also, if
> something out there checks to see whether it's handling a PyCFunction
> and then manipulates the guts of the object on that basis, it might
> get unexpected results.  I can't think of any other problems, but it's
> possible they're lurking.  If I wanted to really know I'd have to go
> review what happens when you subclass a built-in type that way... and
> it's probably not documented, so that would mean reading the Python
> source.

We need a volunteer to do this research and to figure out what is wrong when
using Python 2.3 and 2.4.

> Also, for functions with overloads, only one of the docstrings
> is printed out. It looks like
> 
> void function::add_to_namespace(
>     object const& name_space, char const* name_, object const& attribute,
> char const* doc)
> 
> just replaces the old doc string instead of appending the new one
> to the old.

Another case for a volunteer...

Sorry that I cannot be more helpful.

Cheers,
        Ralf



		
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