docs: state varchar/char defaults to '' as a rule, not a preference - #271
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dimitri-yatsenko wants to merge 2 commits into
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docs: state varchar/char defaults to '' as a rule, not a preference#271dimitri-yatsenko wants to merge 2 commits into
dimitri-yatsenko wants to merge 2 commits into
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NULL and '' both read as "nothing," and allowing both on a string attribute forces every query and make() body to handle two representations of the same absence. Surfaced by a live example in datajoint-python#1548, whose own new test fixtures defaulted varchar attributes to NULL.
An enum's closed value set is exactly the place to add '' as an explicit member rather than reaching for NULL — no reason to layer a second absence-mechanism on a type that already enumerates its allowed values.
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`definition-syntax.md` already showed `''` as the preferred string default, but phrased the guidance as "prefer" — soft enough that it reads as stylistic rather than enforceable. Strengthens it into a stated rule with the reasoning: `NULL` and `''` both read as "nothing," so allowing both on the same attribute forces every query and every `make()` body to handle two representations of the same absence.
Surfaced by a live example: `datajoint-python#1548`'s own new test fixtures defaulted `varchar` attributes to `NULL` rather than `''`.