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    <p>There is an easy way to make python properties from methods with swig.<br> Suppose C++ code Example.h:</p> <p><strong>C++ header</strong></p> <pre><code>class Example{ public: void SetX(int x); int GetX() const; }; </code></pre> <p>Lets convert this setter and getter to python propery 'x'. The trick is in .i file. We add some "swiggy" inline python code (with %pythoncode) that is inserted in a body of a resulting python class (in the auto-generated python code).</p> <p><strong>Swig wrapping Example.i</strong></p> <pre><code>%module example %{ #include "example.h" %} class Example{ public: void SetX(int x); int GetX() const; %pythoncode %{ __swig_getmethods__["x"] = GetX __swig_setmethods__["x"] = SetX if _newclass: x = property(GetX, SetX) %} }; </code></pre> <p>Check the python code:</p> <p><strong>python test code</strong></p> <pre><code>import example test = example.Example() test.x = 5 print "Ha ha ha! It works! X = ", repr(test.x) </code></pre> <p>That is it!</p> <hr> <hr> <h2>Make it simplier!</h2> <p>There is no need to rewrite a class definition. Thanks to Joshua advice, one could use SWIG directive %extend ClassName { }. </p> <p><strong>Swig wrapping Example.i</strong></p> <pre><code>%module example %{ #include "example.h" %} %extend Example{ %pythoncode %{ __swig_getmethods__["x"] = GetX __swig_setmethods__["x"] = SetX if _newclass: x = property(GetX, SetX) %} }; </code></pre> <h2>Hiding setter and getter functions</h2> <p>As one may see, test.GetX() and test.SetX() are still in place after conversion. One can hide them by:</p> <p>a) Rename functions by using %rename, add '_' in the beginning thus making methods "private" for python. In the a SWIG interface .i Example.i</p> <pre><code>... class Example{ %rename(_SetX) SetX(int); %rename(_GetX) GetX(); ... </code></pre> <p>(%rename may be placed in some separated place to save the possibility to convert this class to other languages, which don't need these '_')</p> <p>b) or one can play with %feature("shadow")</p> <h2>Why is it so?</h2> <p>Why do we have to use such things to convert methods to a property by using SWIG? As it was said, SWIG selfishly overrides <strong>_<em>setattr</em>_</strong>, so one have to use <strong>_swig_getmethods_</strong> and <strong>_swig_setmethods_</strong> to register functions and stay in the swig way. </p> <h2>Why may one prefer this way?</h2> <p>The methods listed above, especially with PropertyVoodoo are... It is like burning the house to fry an egg. Also it breaks the classes layout, as one have to create inherited classes to make python properties from C++ methods. I mean if class Cow returns class Milk and the inherited class is MilkWithProperties(Milk), how to make Cow to produce MilkWithProperties?</p> <p>This approach allows one to:</p> <ol> <li><strong>explicitly control what C++ methods to convert to python properties</strong></li> <li>conversion rules are located in swig interface(*.i) files, the place where they are supposed to be</li> <li>one resulting autogenerated .py file</li> <li>stay in the swig syntax of insertions in swig generated .py file</li> <li>%pythoncode is ignored if one wraps library to other languages</li> </ol> <p><strong>Update</strong> In a newer version SWIG abandoned <strong>_swig_property</strong> so just use <strong>property</strong>. It works with old version of swig the same. I've changed the post. </p>
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    1. COthank you! This seems to work beautifully. In case others find it helpful, remember that with swig you can use%extend ClassName { } to add methods to the class from within the interface file when the class is defined in separate header files. I believe that this method will even work when you overload your C++ getter and setter with the same name.
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    2. COI will have to try your answer out the next time I need to do some swig and python. I this is more of the solution I was looking for if it does indeed work as advertised.
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