Re: Custom streamer example

Hi Vassili,

This information is in the Users Guide. see page 173 of http://root.cern.ch/download/doc/11InputOutput.pdf Look at section "Streamers with Special Additions"

Rene

 Maroussov wrote:
> Dear Rene and Axel,
>
> thank you so much for your advices. I think the Rene's recipe (if you
> want a custom streamer, first take a look at the automatically
> generated one) should be in the "Streamers with Special Additions"
> chapter of the ROOT Users Guide . The recipe looks absolutely
> trivial... when you know it.
>
> Regards,
>
> Vassili
>
> On 10/07/2010 12:50 PM, Rene Brun wrote:
>> 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
>>>
>>>
>>>
>>>
>>
>
Received on Thu Oct 07 2010 - 15:49:12 CEST