netclass.via_diameter

What it is ¶

netclass.via_diameter(class, mm) yields the via pad diameter that a net class DECLARES for its nets, held in metres and shown in mm, one row per class that states one. A class that states none yields no row. That absence is a meaningful fact rather than a gap, because the field then cascades to a lower-priority class.

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.

There is no conformance check on this one yet. The board tier projects via DRILL but not via pad diameter, so there is nothing yet to compare this against.

For software engineers ¶

Keyed by CLASS, not by net, and there is no cascaded per-net counterpart for this quantity. Only net.declared_track_width and net.declared_via_drill are derived, because only those two have a board-tier actual to be compared against (WS3-111 scope). Do not join this to net.netclass and treat the result as a per-net limit, because a net in several classes matches several rows. Resolving which one wins is the cascade, and this relation deliberately does not do it for you.

Go projector ¶

netClassDefFacts in stdlib/relations/facts.go walks Model.NetClassDefs(), the ir.Constraint nodes of kind netclass, and parses the via_diameter 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. The marker 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. A project can assign nets to a class it never defined.

Datalog ¶

Every class and its declared value:

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