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 Post subject: Optimizing non-static member function
PostPosted: Sun Feb 06, 2022 6:29 pm 
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Joined: Sun Feb 06, 2022 6:24 pm
Posts: 9
Hi Everyone,

I need to optimize a function that is a non static member of the class. Because I can't pass a pointer to a non static member function, this command return an error:

Code:
minlmoptimize(state, func);


How can I pass the pointer to the function, considering that I can make it static?


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 Post subject: Re: Optimizing non-static member function
PostPosted: Sun Feb 06, 2022 10:03 pm 
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Joined: Fri May 07, 2010 7:06 am
Posts: 880
minlmoptimize() accepts additional ptr parameter (NULL by default) that is forwarded to the callback func.

You can make a wrapper function that accepts void* pointer, converts it to the pointer to an instance of your class and calls its method. Correct me if I wrong, but you may even use lambdas to create a wrapper function (if you refrain from capturing local variables - such lambdas can't be converted to function pointers).


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 Post subject: Re: Optimizing non-static member function
PostPosted: Sun Feb 06, 2022 11:25 pm 
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Joined: Sun Feb 06, 2022 6:24 pm
Posts: 9
Yes, I think using lambdas is the best way, but I can't find the correct syntax.
I have tried this:

Code:
minlmoptimize(state, [](auto _) {return fun(_); });


where fun is defined as:

Code:
void myClass::fun(const real_1d_array& X, real_1d_array& f, void* ptr){...}


But this doesn't work because it doesn't recognize this lambda as a pointer to "fun". Where am I wrong?


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 Post subject: Re: Optimizing non-static member function
PostPosted: Mon Feb 07, 2022 3:05 pm 
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Joined: Fri May 07, 2010 7:06 am
Posts: 880
You should change lambda signature to match that of the callback accepted by minlpoptimize: (const real_1d_array& X, real_1d_array& f, void* ptr). What you have here can be cast to pointer to function, but this pointer has completely different signature.


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 Post subject: Re: Optimizing non-static member function
PostPosted: Mon Feb 07, 2022 3:39 pm 
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Joined: Sun Feb 06, 2022 6:24 pm
Posts: 9
Thanks Sergey for your answer, but every syntax I try, it gives me an error.
Could you show me exactly what I should type?


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