Add integer support to TVectorT

[ynikitenko]

Is your feature request related to a problem? Please describe.

I'd like to store a vector of integers in a TFile. Rene Brun suggested using TVectorD for doubles, but I'd like to store integers (to store them in the vector of doubles is possible, but less convenient).

TVectorT has support only for floats and doubles. As of 2011, it doesn't support integers.
But I think it would be nice to add that support.

When I try to use TVectorT<int> in ROOT 6.24/00, ld gives an error:

undefined reference to `TVectorT::TVectorT(int)'

Describe the solution you'd like

Add support for TVectorT<int> and a TVectorI shortcut (would be easier to use that from Python).

Describe alternatives you've considered

@pcanal proposed such a code,

struct VectorWrapper : public TObject {
    std::vector<int> fContent;
    ClassDef(VectorWrapper, 2);
};

and to generate, compile and link a dictionary for that. However, it would take much more time than to use a ready class.

[pcanal]

You can now just use std::vector<int> directly:

std::vector<int> v;
...
f->WriteObject(&v, "somename");

For quite a while now, inheriting from TObject is no longer a requirement for storing an object in a TFile

Cheers,
Philippe.

[ynikitenko]

Hi Philippe, thanks for the info!

I'll try that. It's a pity that I couldn't find a more recent answer to that question during the search.
Is there a recent way to write one value to a ROOT file, e.g. a double?

Cheers,
Yaroslav

[pcanal]

For numerical type, you would use TParameter<double> (i.e. you still need a class for data stored directly in a TFile/TDirectory. You do not need an object if the data is stored in a TTree).

[ynikitenko]

Thanks, Philippe. I added that information to the old thread on the forum. I also found what you were saying in the manual (so it is present somewhere in the documentation, though I usually read the reference guide).
About my initial feature request: I think this is a continuous wish of users to have a vector for ints (and other types) when you have a vector for doubles. So it's up to you whether you add this support or not (me personally no longer need that).

[dpiparo]

Closing since the original need has been clarified and addressed with the regular IO capabilities.