A question about TClass::New(..)

ROOT
1

Dear you,

I have a question a bout TClass::New(…), this maybe a silly question, but useful for me.

I have a code like this,

const char* cname = "UserClassName";
//by useing the TClass::New(..) method, I can create an object of 'UserClassName'
void *obj = gROOT->GetClass(cname)->New(0);

the ‘obj’ is a ‘void*’ type, my question is how can I cast ‘obj’ to it’s true type ‘UserClassName’ [color=#FF0000] by using the value of ‘cname’[/color].
I mean I want to do something like:

(static_cast<cname>(obj))->somemethod(...);

if I do not cast ‘obj’ to it’s true type, I can not excute it’s member functions.

Any help or advice is appreciated!
Han

2

Hi,

This can not be done directly in compiled code, however you can go through the interpreter. One way is:gROOT->ProcessLine(TString::Format("((%s *)%p)->somemethod()",cname,obj);Alternatively you can go through the TClass and TMethodCall interface.

Cheers,
Philippe.

3

Thanks pcanal.
Your method is useful, it works well.

Best regards.
Han