netclass.via_drill

What it is ¶

netclass.via_drill(class, mm) yields one row for each net class that DECLARES a via drill diameter for its nets. The value is held in metres and shown in mm. A class that states no via drill diameter yields no row. That absence is a meaningful fact rather than a gap, because the field then cascades to a lower-priority class.

This is the DECLARED side. board.via_drill(net, mm) is the ACTUAL side, in the same units, so the two join without conversion.

For hardware engineers ¶

This is the number you typed into Board Setup for that class, read back. Query it to confirm the engine sees the constraints you set, and to check the project against itself. The declared drill records what you intended, and the routed drill records what happened. A review that compares the two contains no number the tool invented.

For software engineers ¶

Keyed by CLASS, not by net, and it is NOT what a rule should compare against. A net can be in several classes, so joining net.netclass to this relation fans out and compares the net’s copper against EVERY class it belongs to. A net correctly routed at its winning class’s drill will then “fail” against a losing class’s. Join net.declared_via_drill(net, mm) instead, which resolves the cascade first. This relation exists for introspection and for authoring, not for comparison.

Go projector ¶

netClassDefFacts in stdlib/relations/facts.go walks Model.NetClassDefs(), the ir.Constraint nodes of kind netclass, and parses the via_drill param. Populated in the I/O layer by kicad.AnnotateNetClassDefs from the sibling .kicad_pro net_settings.classes[] (WS3-111).

Absence is not a pass ¶

Only a KiCad project read populates this. An EDIF netlist, an IPC-2581 board, a bare .kicad_sch, and a KiCad project that defines no classes all leave it empty, and a rule scoped by it would find nothing and read clean. design.has_netclass_defs separates those cases. It is deliberately distinct from design.has_netclass, because membership and definitions are independent blocks of net_settings. So a project can assign nets to a class it never defined.

Datalog ¶

Every class and its declared drill:

netclass.via_drill(?class, ?mm) => ?class, ?mm