Re: programmatically create a TClass at runtime

Hi Sebastien,

The work need is similar to the work done by Cintex for Reflex. For example the answer to your direct question is somewhat in the file cint/cintex/src/ROOTClassEnhancer.cxx

Cheers,
Philippe.

On 5/4/11 12:00 PM, Sebastien Binet wrote:
> hi there,
>
> I am playing with Go (the language at golang.org) and trying to see if
> one could use ROOT as an I/O back-end.
>
> Go has built-in reflection capabilities so theoretically any Go struct
> can be described at runtime/compiletime and converted to a Reflex or
> CINT metadata.
> Moreover, Go-struct usually have the same layout than their C cousin
> (that's not true for Go-strings and Go-slices (which are views into
> arrays))
>
> the amount of work on my side to be able to support the below kind of
> code should be rather minimal:
>
> // ---
> type MyStruct struct {
> IntData [10]int32
> FloatData [20]float64
> }
>
> f := ROOT.NewFile("foo.root", "recreate")
> t := ROOT.NewTree("tree", "title")
> s := MyStruct{}
> t.Branch("mystruct",&s) //<---
> // ---
>
> From my end, I would need to create a ROOT::TClass instance for the
> Go-struct MyStruct leveraging Go's "reflect" package which knows the types
> and offsets of each data member.
>
> is this possible without reaching to automatically generated code ?
> (rootcint|genreflex)
> that would simplify the amount of infrastructure to provide...
>
> -s
>
> PS: right now, I am just unfolding the struct and register branches like
> so (in pseudo-code):
> for f := range typ.Fields() {
> s := "mystruct_"+f.Name()
> field_addr := obj.Address()+f.Offset()
> branch_typ := s+"/"+go2ctype[f.Type()].Name()
> tree.Branch(s, field_addr, branch_typ)
> }
>
Received on Wed May 04 2011 - 19:43:00 CEST