Qt and muParser

[RavenS]

Good evening.
Someone used muParser? (http://muparser.sourceforge.net/) I am interested in how you can embed it in the Qt-application.
My attempts is not allowed. Displays a lot of errors, in particular, "undefined reference to `vtable for mu:: Parser '"

[lyuts]

Did you add the path to muParser's libs to DEPENDPATH variable in your .pro file?

[RavenS]

Yes, i solved this problem, but i can't understand what to do with the next error:
"no matching function for call to `mu::Parser::DefineFun(const char[7], <unknown type>, bool)'"

It seems that my callback function have invalid declaration, but i just copied example code and tried to compile it. I tried to use mu::value_type as type of returning value, but it still doesn't works.

[lyuts]

Can you show us some code?

[RavenS]

Here it is.

#include "someClass.h"
#include <QString>
 
#include <muParser.h>
 
double someClass::MyFunction(double a_fVal)
{
  return a_fVal*a_fVal;
}
 
double someClass::eval()
{
  using namespace mu;
  try
  {
    double fVal = 1;
    Parser p;
    p.DefineVar("a", &fVal);
    p.DefineFun(_T("MyFunc"), MyFunction, false);
    p.SetExpr("MyFunc(a)*_pi+min(10,a)");
    return p.Eval();
  }
  catch (Parser::exception_type &e)
  {
    qDebug() << "Error!";
    //std::cout << e.GetMsg() << endl;
  }
 
  return 0;
}

#include "someClass.h"
#include <QString>

#include <muParser.h>

double someClass::MyFunction(double a_fVal)
{
  return a_fVal*a_fVal;
}

double someClass::eval()
{
  using namespace mu;
  try
  {
    double fVal = 1;
    Parser p;
    p.DefineVar("a", &fVal);
    p.DefineFun(_T("MyFunc"), MyFunction, false);
    p.SetExpr("MyFunc(a)*_pi+min(10,a)");
    return p.Eval();
  }
  catch (Parser::exception_type &e)
  {
    qDebug() << "Error!";
    //std::cout << e.GetMsg() << endl;
  }

  return 0;
}

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When i'm trying to compile i get this:
"no matching function for call to `mu::Parser::DefineFun(const char[7], <unknown type>, bool)'"

This is a little example on http://muparser.sourceforge.net/mup_...html#idExample :

#include "muParser.h"
 
// Function callback
double MyFunction(double a_fVal) 
{ 
  return a_fVal*a_fVal; 
}
 
// main program
int main(int argc, char* argv[])
{
  using namespace mu;
 
  try
  {
    double fVal = 1;
    Parser p;
    p.DefineVar("a", &fVal); 
    p.DefineFun("MyFunc", MyFunction); 
    p.SetExpr("MyFunc(a)*_pi+min(10,a)");
    std::cout << p.Eval() << endl;
  }
  catch (Parser::exception_type &e)
  {
    std::cout << e.GetMsg() << endl;
  }
  return 0;
}

#include "muParser.h"

// Function callback
double MyFunction(double a_fVal) 
{ 
  return a_fVal*a_fVal; 
}

// main program
int main(int argc, char* argv[])
{
  using namespace mu;

  try
  {
    double fVal = 1;
    Parser p;
    p.DefineVar("a", &fVal); 
    p.DefineFun("MyFunc", MyFunction); 
    p.SetExpr("MyFunc(a)*_pi+min(10,a)");
    std::cout << p.Eval() << endl;
  }
  catch (Parser::exception_type &e)
  {
    std::cout << e.GetMsg() << endl;
  }
  return 0;
}

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As you can see, they are equal.

[lyuts]

Well, they are not equal. I don't know the exact signature, as well as _T function but
your code has a call passing a bool variable

p.DefineFun(_T("MyFunc"), MyFunction, false);

p.DefineFun(_T("MyFunc"), MyFunction, false);

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While example code has this call

p.DefineFun("MyFunc", MyFunction);

p.DefineFun("MyFunc", MyFunction);

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[lyuts]

Ok, sorry...
I got the correct signature

inline void DefineFun(const string_type &a_strName, TYPE a_pFun, bool a_bAllowOpt = true)

inline void DefineFun(const string_type &a_strName, TYPE a_pFun, bool a_bAllowOpt = true)

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Then, i have just noticed, that the example is passing the a regular function, while you are trying to to pass a function that is a class member.

[RavenS]

I found this expression in additional muParser examples, and tried, but in this case it doesn't work too.
Not first, nor second variant.

[RavenS]

Wow! It works!
Thank you very much!

[lyuts]

By the way, take a look at this

http://www.parashift.com/c++-faq-lit....html#faq-33.2