Hi Pere,
The answer to your 3 questions is to use TMethodCall. A small example:
void pere() {
// example illustrating the use of TMethodCall
void pere() {
// example illustrating the use of TMethodCall
//create a TMethodCall for the TLine constructor
TMethodCall mc,mcdraw;
mc.InitWithPrototype(TLine::Class(),"TLine","double,double,double,double");
mcdraw.InitWithPrototype(TLine::Class(),"Draw","const char*");
Long_t l,ldraw;
TRandom r;
char params[100];
//draw 100 lines
for (int i=0;i<100;i++) {
sprintf(params,"%f,%f,%f,%f",r.Rndm(),r.Rndm(),r.Rndm(),r.Rndm());
mc.Execute(0,params,l);
mcdraw.Execute((TLine*)l," ",ldraw);
}
}
In the InitWithPrototype call, you can specify any complex type:
- basic type,
- class
- pointer, etc
to pass a pointer, simply encode the value of the pointer, eg for a TLine*
sprintf(params,"(TLine*)0x%x",line); //where line is a TLine*
Rene Brun
Pere Mato wrote:
>
> Hi All,
>
> I am trying to make an exercise of interfacing ROOT with Python using the
> API provided by the ROOT Meta classes (TClass, TMethod, TDataMember, etc.)
> and I have several questions:
>
> - How to call a constructor with arguments. The method TClass::New() calls
> only the default constructor. I naively tried to call the class constructor
> method as a normal method using TObject::Execute(...) immediately after the
> object has been created with TClass::New() but it does not seem to work.
>
> - How to get the return value of a function/method call. The method
> TObject::Execute(...) does not give you this possibility. Also the method
> TMethodCall::Execute(...) allows only to return either a long, double or a
> string but nothing else.
>
> - How I can pass a "complex" data type as an argument to a method. In
> particular, how I can give a TObject* as argument. The way I understand the
> method TObject::Execute() works is by constructing a string with comma
> separated argument values. In the case of being within the CINT interpreter
> it seems that you can pass the name of a CINT variable pointing to your
> complex data type. But if you are not in CINT, which is exactly my case I do
> not see how I can do it.
>
> Thanks in advance for any hint or suggestion,
>
> ------------------------------------------------------------
> Pere Mato CERN, EP Division, CH 1211 Geneva 23, Switzerland
> e-mail: Pere.Mato@cern.ch tel: +41 22 76 78696
> fax: +41 22 76 79425 gsm: +41 79 20 10855
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