Just-In-Time Compilation with Classes

Newbie
1

I’m trying to use Jitting with Classes but am having issues. I’ve been trying to run the following test code (just to see if I can get it to work):

cpp_code = """
class TestClass
{
    private:
        int num;
        
    public:
        TestClass(int num);
        int ReturnNum();
};

TestClass::TestClass(int num)
{
    this->num = num;
}

int TestClass::ReturnNum()
{
    return this->num;
}
"""

And then running:

ROOT.gInterpreter.ProcessLine(cpp_code)

mocm = ROOT.TestClass(17)
mocm.ReturnNum()

And the error message is:

input_line_53:17:12: error: qualified reference to ‘TestClass’ is a constructor name rather than a type in this context
TestClass::TestClass(int num)
^
input_line_53:17:26: error: expected ‘(’ for function-style cast or type construction
TestClass::TestClass(int num)

I’ve been able to get jitting to work for just straight up functions, but not for classes. What am I doing wrong?

Please read tips for efficient and successful posting and posting code

ROOT Version: Not Provided
Platform: Not Provided
Compiler: Not Provided

2

Hi @Diracula ,
I think ProcessLine tries to execute the code and trips up on the fact that the code is not executable. You want Declare in this case:

In [1]: import ROOT

In [2]: code = """
   ...: class TestClass
   ...: {
   ...:     private:
   ...:         int num;
   ...:
   ...:     public:
   ...:         TestClass(int num);
   ...:         int ReturnNum();
   ...: };
   ...:
   ...: TestClass::TestClass(int num)
   ...: {
   ...:     this->num = num;
   ...: }
   ...:
   ...: int TestClass::ReturnNum()
   ...: {
   ...:     return this->num;
   ...: }
   ...: """

In [3]: ROOT.gInterpreter.Declare(code)
Out[3]: True

In [4]: t = ROOT.TestClass(17)

In [5]: t.ReturnNum()
Out[5]: 17

Cheers,
Enrico

3

Sorry, I did that, but forgot to include it in the code. I’ve amended the code to reflect that.

4

The trick is using Declare instead of ProcessLine, see my example above (if you scroll down you can see the full working example).

6

Oh, sorry, I misunderstood your response (for some reason). That worked, thanks!