Re: std::vector<Bool_t> in PyROOT

Hello Wim and Axel,

Kevin kindly told me that vector<bool> is a special template in the C++ standard and thus it is different from other vectors such as vector<int>... I did not know this in fact.

> I don't have a solution for you, but perhaps it will help out.
> std::vector<bool> is NOT a directly indexable container ... in fact, the
> standard specifies std::vector<bool> as a specialization with different
> semantics that the base std::vector<T> template. It can't be directly
> indexed or iterated; it requires proxy objects.
>
> See, for instance, http://www.gotw.ca/gotw/050.htm and
> http://www.gotw.ca/publications/N1211.pdf

However, at least GCC4 on Mac can handle vector<bool> as a user (who is lacking this knowledge) expected. This test code compiles and runs as expected. So I was wondering if CINT also could handle vector<bool> as GCC does, although I can avoid this "feature" using vector<int> or similar.

int main()
{
  std::vector<bool> v(100);   

  for(int i = 0; i < 100; i++){
    v[i] = i%2 == 0 ? true : false;
    std::cout << v[i] << std::endl;
  } // i

  return 0;
}

Regards,

--
OKUMURA, Akira oxon@{astro.isas.jaxa.jp,stanford.edu}
Institute of Space and Astronautical Science (ISAS/JAXA)
Now at KIPAC/SLAC/Stanford
Varian Physics #306
382 Via Pueblo Mall, MC 406 Stanford, CA94305
TEL 650-736-0971/FAX 650-724-5065
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On 2010/06/28, at 21:41, WLavrijsen_at_lbl.gov wrote:



> Tim,

> 

>> It doesn't, well __getitem__() is missing:


> 

> hmm, something with the dictionary than. I'm afraid we'll have to wait

> until Axel wakes up, as the problem is there in CINT also:

> 

> [pc3-wlav] ~/rootdev/root % root -b -l

> root [0] #include <vector> root [1] std::vector<bool> v; root [2] v.push_back(false); root [3] v.push_back(true); root [4] std::cout << v.size() << std::endl;

> 2

> root [5] std::cout << v[0] << std::endl; Error: Can't call vector<bool,allocator<bool> >::operator[]((int)0) in current scope (tmpfile):1:

> Possible candidates are...

> (in vector<bool,allocator<bool> >)

> *** Interpreter error recovered ***

> root [6]

> 

>> How do you get a dictionary to be loaded and why do the others get
>> loaded automagically?


> 

> Long story. In short: some std::vector instantiations are "shipped" with

> CINT, others are auto-generated, yet others are found through the ROOTMAP

> or LDPATH search paths if e.g. setup within an experiment runtime.

> 

> Best regards,

>           Wim

> -- 

> WLavrijsen_at_lbl.gov    --    +1 (510) 486 6411    --    www.lavrijsen.net