Semi-optional keyword args in Python RNG wrappers about galsim HOT 2 CLOSED

I tend to avoid using bp::optional<> (and the BOOST_PYTHON_FUNCTION_OVERLOADS macros) for exactly this reason, even though it's what you'll find in the Boost.Python tutorial.

Instead you can duplicate the default values when telling Boost.Python about the keyword arguments; in this case, that's
(bp::arg("u_"), bp::arg("mean")=0., bp::arg("sigma")=1.)

The downside is that you have to put the defaults in two places and keep them in sync. The upside is that keyword arguments now work just like they do in Python.

By the way, I tend to also rename C++ arguments sometimes when specifying the Python keyword arguments. In C++, the argument names aren't used by the caller, and they can have funny names for technical reasons (like u_ instead of u). We don't have to make them the same in both places, and I'd recommend changing the Python keyword argument in this case to something more descriptive (e.g. "uniform"), or at least dropping the _.

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Hi Jim,

Great, thanks!

On 28 Mar 2012, at 09:30, Jim Bosch wrote:

I tend to avoid using bp::optional<> (and the BOOST_PYTHON_FUNCTION_OVERLOADS macros) for exactly this reason, even though it's what you'll find in the Boost.Python tutorial.

Instead you can duplicate the default values when telling Boost.Python about the keyword arguments; in this case, that's
(bp::arg("u_"), bp::arg("mean")=0., bp::arg("sigma")=1.)

The downside is that you have to put the defaults in two places and keep them in sync. The upside is that keyword arguments now work just like they do in Python.

By the way, I tend to also rename C++ arguments sometimes when specifying the Python keyword arguments. In C++, the argument names aren't used by the caller, and they can have funny names for technical reasons (like "u_" instead of "u"). We don't have to make them the same in both places, and I'd recommend changing the Python keyword argument in this case to something more descriptive (e.g. "uniform"), or at least dropping the "_".

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Barnaby Rowe

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