DPL Analysis: use compile-time hashed histogram names in registry

[mario-krueger]

No description provided.

[ktf]

Can you remove the WIP when you are done? LGTM.

[mario-krueger]

Hi @njacazio ,
this commit changes the interfaces of the registry for .fill() and .get().
We want to have the histogram names hashed only once at compile time and not every time we use it in the access functions.
This introduces a bit of an inconvenience for your code since now it is no longer possible to do things like:

for (int i = 0; i < Np; i++) {
  histos.fill(HIST(hexpected[i]), mom, exp[i]);
  histos.fill(HIST(hexpected_diff[i]), mom, t.tpcSignal() - exp[i]);
}

as the name used to fill the histogram cannot be depending on a running index any longer (since this variable is not fixed at compile time).
I have provided a workaround for your code. Maybe you can have a look if this is fine with you (it is put in a separate commit so it can be reverted more easily if needed).
These were rather invasive changes and it might be good if you could confirm that your tasks still work as expected after applying these modifications.

[njacazio]

@mkruegerGitHub thanks for the information! I will try your patch and check !