Redesign version management of streamers about unroot.jl HOT 3 OPEN

Oh dear, I somehow forgot to answer this. I thought I did 🤔

Anyways, the construction of the struct and also the complete parsing of the structures is very complex. There is a Google group where I also participate in and we were already thinking about writing a book or so about the ROOT I/O to consolidate our knowledge. But I don't know about the time-scale, probably not this year...

So indeed, it's hard to answer your question as it's also depending on other fields in TKey, which have magic values, for example listed here: https://github.com/tamasgal/UnROOT.jl/blob/1d892e7b9159e5425ea91a6cc16dabc1caa09b77/src/constants.jl#L27

from unroot.jl.

created dynamically
(later it will define it from the streamer info)

I have time and started looking at the code base again. I'm wondering if it's possible to document an implementation-independent way in a Developers / Internals section of the docs so people can understand how conceptually it works.

Particularly, I am yet to understand how to make a struct for a streamer that we have never seen before, my guess is that the name of streamer and byte # for each field are encoded in TKey(?) or somewhere, but if that is the case does this mean we don't have to do any bootstrap except for the TKey(which is ~fixed) and the starting 37(or 75) bytes of the .root files?

from unroot.jl.

Worth to mention, a Macro posted by Chris Rackauckas on twitter:

macro def(name, definition)
  return quote
      macro $(esc(name))()
          esc($(Expr(:quote, definition)))
      end
  end
end

@def myfields
   x::Int
   y::Int
end

struct A
  @myfields
  z::Int
end

With this macro, anyone can compile-time paste code around.

from unroot.jl.