[ntuple] support rules with source class != dest class

[jblomer]

Including class rename rules.

[github-actions]

Test Results

    18 files      18 suites   4d 7h 6m 17s ⏱️
 2 738 tests  2 738 ✅ 0 💤 0 ❌
47 611 runs  47 611 ✅ 0 💤 0 ❌

Results for commit acade47.

♻️ This comment has been updated with latest results.

[ferdymercury]

Maybe related: https://its.cern.ch/jira/browse/ROOT-114

[hahnjo]

LGTM, see Giacomo's comment about a typo.

Note that, if I remember correctly, it is also possible to write entire class rename rules with only sourceClass and targetClass, but no source and target. I believe then all members are subject to automatic evolution, but should be checked. In a first implementation, we could require explicit copying of all members by the rule.

[pcanal]

Note that, if I remember correctly, it is also possible to write entire class rename rules with only sourceClass and targetClass, but no source and target.

That is accurate and nicked named 'renaming rule'

I believe then all members are subject to automatic evolution, but should be checked. In a first implementation, we could require explicit copying of all members by the rule.

This would be sub-optimal as this would mean that for 'renamed' classes (using that type of rule), individual members/column would not be readable on their own; you would have to read the whole object 'all' the time.

[pcanal]

#pragma link C++ options=version(3) class OldName<int>+;

is more typical white spacing.