[Python] Deprecate conversion from Python set to RooArgSet#22657
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This conversion can lead to subtle problems because Python sets are
unordered, different from C++ initializer lists with the same syntax.
This can lead to confusion that we should prevent.
Example:
```python
import ROOT
x = ROOT.RooRealVar("x", "x", 1.0)
y = ROOT.RooRealVar("y", "y", -1.0)
ROOT.RooArgSet(set([x, y])).Print()
ROOT.RooArgSet(set([y, x])).Print()
```
Gives on my system:
```txt
RooArgSet:: = (x,y)
RooArgSet:: = (x,y) <--- reverse order expected!
```
This is not even deterministic, because Python doesn't guarantee that
a `set` is ordered in any way.
I introduced this 5 years ago in commit c54c324
(PR root-project#8751) whithout thinking
too much about this footgun.
This pattern should not be used, because it leaves the RooArgSet in a non-deterministic ordering, depending on the implementation of Python.
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This conversion can lead to subtle problems because Python sets are
unordered, different from C++ initializer lists with the same syntax.
This can lead to confusion that we should prevent.
Example:
Gives on my system:
This is not even deterministic, because Python doesn't guarantee that
a
setis ordered in any way.I introduced this 5 years ago in commit guitargeek@c54c324
(PR #8751) whithout thinking
too much about this footgun.
guitargeek
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