Streamer for own class

ROOT
1

Hi,
I have the two questions about streamer for own class.

  1. Data (class A) were written into the tree with split unequal -1, the streamer of class A was generated automatically. Later class A was modified globally (parent class was added, some class members were deleted or moved into the parent class etc.), therefore own streamer was written for the class A.
    Question: How can I read the old data by using new version of library and own streamer (for class A)?

  2. Can I write own streamer for class A and use the schema evolution, if the class A is not inherited from TObject?

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[quote]2) Can I write own streamer for class A and use the schema evolution, if the class A is not inherited from TObject?[/quote]Yes. You can simply add a ClassDef macro or write your own free standing streamer and add attach it to the TClass object (for example via the macro RootStreamer(MyClass,MyFreeStandingStreamer).

[quote]1) Data (class A) were written into the tree with split unequal -1,[/quote]If you mean that the branch was actually split, then, currently, there is no easy way to support major changes to the classes (the current most practical solution is to have in memory 2 classes A and Anew and read the data into an object of class A and then translated it after the fact into an object of class Anew).

Cheers,
Philippe.