Merging root files with custom classes

[pdudero]

@dpiparo

we take note of your request for a better documentation about mergeable classes: we’ll take an action about this.
For the time being, did you try to implement for your classes a Merge method like the one of TH1, i.e. with the signature Long64_t MyClass::Merge(TCollection*)?

No, I had assumed that there was documentation to show me how. I got that idea from this post, where the poster refers vaguely to “the documentation”.

Making TFileMerger Compatible Classes

Hi, Classes that are not compiled (via ACLiC or via rootcint + compiler) are not support in I/O (and thus not by the TFileMerger). [quote]Inheriting from TKey and setting fClassName stores the class name properly. [/quote]Unless you have a very unusual use case, your object should NOT inherit from TKey. The way things works is that you stored on object via: mydirectory->WriteObject(objptr,"name");which streams your object into a memory buffer, create a TKey with the right information (…