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ALL-CLAS0004 · declared_field_count

Measure the widest data surface one type in this module declares.

This is a deterministic rule for all languages. Read its implementation.

Definition

Section titled “Definition”

Group every data member this module declares by the type that owns it and return the largest group. A data member is state a reader has to hold in mind for every method of the type, so the width of the widest type is what says whether the file asks too much. Counting is by resolved declaration rather than by syntax, so a name a type states once in its body and again in its initializer is one member, not two.

Every language that attaches state to a type takes part, and each one spells the declaration differently. A Rust struct field, a TypeScript property, a C++ member, a Python class-body annotation, and a Python initializer assigning to self all arrive as the same resolved declaration, so one measurement covers them.

Reading the whole module at once is what makes the measure affordable. Ownership comes from the qualified name each declaration already carries, so nothing has to be re-resolved and a type split across an interface and its implementation still counts once.

Evidence

Section titled “Evidence”

Each finding records the module range and every data member grouped under the type declaring it. The value is the size of the largest group.

Exceptions

Section titled “Exceptions”

Callables are counted by the neighboring public-method rule, because a wide record and a wide interface are two different defects. A module declaring no type at all measures zero. The count is a measurement, and a project policy owns the ceiling, since a serialized message and a service object tolerate very different widths.

Examples

Section titled “Examples”

A class whose initializer assigns self.host, self.port, and self.timeout returns 3, and a dataclass stating the same three names as annotations returns 3 as well. A class stating host: str in its body and assigning self.host in its initializer counts host once, so it returns 1. A module declaring only functions returns 0.

References

Section titled “References”