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POctypes class member access segfaulting
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  1. POctypes class member access segfaulting
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    copied!<p>I'm interested in using a c++ class in python. Looking at <a href="https://stackoverflow.com/questions/145270/calling-c-c-from-python">Calling C/C++ from python?</a>, I decided to try ctypes. However, I get segfault when I try to change the value of a class member.</p> <p>Here is a simple example that reproduce my problem:</p> <p>The C/C++ side:</p> <pre><code>#include &lt;iostream&gt; class Foo{ private: int mValue; public: void bar(){ std::cout &lt;&lt; "Hello" &lt;&lt; std::endl; } void setValue(int inValue) { mValue = inValue; std::cout &lt;&lt; "Value is now: " &lt;&lt; mValue &lt;&lt; std::endl; } void setValue2() { mValue = 2; std::cout &lt;&lt; "Value is now: " &lt;&lt; mValue &lt;&lt; std::endl; } }; extern "C" { Foo* Foo_new(){ return new Foo(); } void Foo_bar(Foo* foo){ foo-&gt;bar(); } void Foo_setValue(Foo* foo, int v) { foo-&gt;setValue(v); } void Foo_setValue2(Foo* foo) { foo-&gt;setValue2(); } } </code></pre> <p>The code is compile on OSX with:</p> <pre><code>g++ -c -fPIC foo.cpp -o foo.o &amp;&amp; g++ -shared -Wl -o libfoo.dylib foo.o </code></pre> <p>The python side:</p> <pre><code>from ctypes import * lib = cdll.LoadLibrary('./libfoo.dylib') class Foo(object): def __init__(self): self.obj = lib.Foo_new() def bar(self): lib.Foo_bar(self.obj) def set(self, v): lib.Foo_setValue(self.obj, v); def set2(self): lib.Foo_setValue2(self.obj); </code></pre> <p>I can call bar without problem, but I get segfault if I call set or set2.</p> <pre><code>f = Foo() f.bar() # Ok f.set(3) # Segfault </code></pre> <p>Obviously, I'm missing something. </p>
 

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