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    <p><a href="http://misspent.wordpress.com/2009/09/27/how-to-write-boost-python-converters/" rel="noreferrer">This blog post</a> has a pretty clear description of how to write these converters. The basic pattern is to define a class that has the form:</p> <pre><code>struct SomeType_from_PyObject { SomeType_from_PyObject(); static void* convertible(PyObject* obj_ptr); static void construct(PyObject* obj_ptr, converter::rvalue_from_python_stage1_data* data); }; </code></pre> <p>Where the constructor is responsible for adding this converter to Boost.Python's registry:</p> <pre><code>SomeType_from_PyObject::SomeType_from_PyObject() { converter::registry::push_back(&amp;convertible, &amp;construct, type_id&lt;SomeType&gt;()); } </code></pre> <p>The function <code>convertible</code> tells Boost whether or not this converter can convert the specified Python object:</p> <pre><code>void* SomeType_from_PyObject::convertible(PyObject* obj_ptr) { if (PyMapping_Check(obj_ptr)) { return obj_ptr; } else { return NULL; } } </code></pre> <p>The <code>construct</code> function actually creates an object of the conversion type:</p> <pre><code>void SomeType_from_PyObject::construct(PyObject* obj_ptr, converter::rvalue_from_python_stage1_data* data) { typedef converter::rvalue_from_python_storage&lt;SomeType&gt; storage_t; storage_t* the_storage = reinterpret_cast&lt;storage_t*&gt;(data); void* memory_chunk = the_storage-&gt;storage.bytes; object obj(handle&lt;&gt;(borrowed(obj_ptr))); SomeType* output = new (memory_chunk) SomeType(); // Use the contents of obj to populate output, e.g. using extract&lt;&gt; data-&gt;convertible = memory_chunk; } </code></pre> <p>and then in your inside your BOOST_PYTHON_MODULE, include the line</p> <pre><code>SomeType_from_PyObject(); </code></pre>
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    1. COThank you very much for this great post Ray. I started going down this route (and will most likely complete what I was working on to learn a bit more about the Python/C API. I think aleksay's keyword argument method will be how I'll go if I can get it working, but this is very valuable stuff here. +1
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    2. COI agree, while converters is not the way I would solve Mark's problem, I do appreciate a nice post on boost::python converters.
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