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docs(dumpkit): tree output is lossy -- decide whether to document it or fix the writer #1266
Description
Describe the bug
The tree dumper renders '', b'', None, {}, NO_VALUE and NULL all as NIL, so they cannot be told apart; a string containing a newline breaks the layout; and a complex value raises TypeError. Nothing in the docs says the tree format is lossy. This is a question rather than a confirmed defect: tree is a display format.
To Reproduce
make_dumper(dictdumper.Tree) over {'a': '', 'b': b'', 'c': None, 'd': {}, 'e': NO_VALUE, 'f': NULL} prints NIL for all six. {'a': 'x\ny'} prints |-- a -> x then y at column 0. {'c': 1+2j} raises TypeError: must be real number, not complex.
Repro: /tmp/rtissues/dumpkit-repro.py, check D12.
Expected behavior
Decide: state in the dumper docs that tree is a lossy display format, or give each of these a distinct rendering and escape newlines.
Found by the dumpkit round-trip audit (#1202). The repro was re-checked by an independent verifier, and I re-ran it on main at 11ae68ebf.
Activity
JarryShaw commentedon Oct 7, 2026
Decision needed: tree output is lossy.
'',b'',None,{},NO_VALUEandNULLall render asNIL. Newlines inside a string break the layout, and acomplexvalue raisesTypeError. Nothing in the docs says tree output is lossy.complexfrom raising. JSON and plist stay the lossless formats under test: round-trip coverage for every protocol code, dumper and lossless path #1202.My recommendation is (1): nothing parses tree output back, so it has no round trip to keep.
JarryShaw commentedon Oct 7, 2026
take (1)
JarryShaw commentedon Oct 7, 2026
Ruling recorded: option (1). The tree dumper is documented as a lossy, human-readable view, JSON and plist remain the lossless formats under #1202, and a
complexvalue will be rendered rather than raising.Blocked until #1305 merges, because the
complexfix is indumpkit/common.py, which #1305 edits.JarryShaw commentedon Oct 7, 2026
Unblocked: #1305 merged at 20:04Z, so the option-(1) work (document the tree dumper as lossy and stop
complexfrom raising) can start. Back topending.fix(dumpkit): tree output raises on complex and is undocumented as lo…