Handle Print() with FairLogger about fairlogger HOT 5 CLOSED

One option would be to not use TParticle::Print(). Add operator<< to TParticle. Either by patching it in ROOT, or externally in your code, something like:

inline std::ostream& operator<<(std::ostream& os, const TParticle& p)
{
    return os << "TParticle: " << p.GetName() << " " << p.Px() << " " << p.Py() << " " << p.Pz() << " " << p.Vx() << " " << p.Vy() << " " << p.Vz() << " " << p.GetFirstMother() << " " << p.GetMother(); 
}

After this you can change your code to:

TParticle *p = (TParticle *)tr->GetParticle();
LOG(info) << "Stage " << p->GetStatusCode() << " : " << *p;

That would give you the exact same output (unless I have a typo somewhere, but you can achieve it).
Or modify it to get the output you actually want. Like, the operator<< could already include p.GetStatusCode(), remove unneeded fields, etc..

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We could also add another macro that doesn't add a new line.

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There is also a problem with your code. If it is called from multiple threads, the output can become mixed. This would also be the case with the no-new-line-macro.
The operator<< solution doesn't have this issue.

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I think it would be good to have the "no-new-line-macro" because otherwise the output could look in some cases messy.
For p->Print() I would go with your suggested solution of an operator<<.

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The "no-new-line-macro" will not happen because of the outlined potential for threading issues it may cause. Furthermore I would avoid adding any state that is stored between LOG calls in FairLogger. And finally, as Dennis correctly pointed out in one of our meetings - a call to LOG "adds an entry in the log", which makes a new line at the end appropriate.

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