Re: Custom streamer example

Hi Vassili,

see example using the 2 files MyObject.h and MyLinkDef.h Note that the declaration of KLM must precede the declaration of the array.

Run rootcint with
 rootcint -f MyDict.cxx -c MyObject.h MyLinkDef.h

Extract MyObject::Streamer from MyDict.cxx and add the necessary lines computing your 2 pointers ArrL, ArrM after reading the main array.

As a last step modify the MyLinkDef file replacing #pragma link C++ class MyObject;
by
#pragma link C++ class MyObject-;

Rene Brun

Maroussov wrote:
> Dear ROOTers,
>
> my object contains several dynamically allocated arrays of the same
> simple type like:
>
> class MyObject : public TObject {
> ...
> double *ArrK; //[K]
> double *ArrL; //[L]
> double *ArrM; //[M]
> ...
> };
>
> In order to decrease the number of time-consuming new/delete I'd like
> to have the constructor and destructor like
>
> MyObject::MyObject(int K, int L, int M) {
> ...
> ArrK = new double [K+L+M]; //Continuous space
> ArrL = ArrK+K; //for all arrays
> ArrM = ArrL+L;
> ...
> }
>
> MyObject::~MyObject() {
> ...
> delete [] ArrK; //Single delete for all
> ...
> }
>
> But then I cannot use the nice feature of rootcint, the automatic
> streamer generation, since rootcint doesn't accept expressions like
> //[K+L+M] (is it still correct for rootcint7 ?). Could you please
> recommend a good simple example of the custom streamer in the ROOT
> source tree (the Event.h mentioned in the "Streamers with Special
> Additions" chapter of the ROOT Users Guide 5.26 actually uses an
> automatically generated streamer)?
>
> Regards,
>
> Vassili
>
>
>
>