symdef

Standard-agnostic toolkit for graphical-symbol data. Symbols are TOML files; the toolkit loads them, resolves composition, lints the wiring contract, renders SVG, and builds a resolved JSON bundle plus a gallery. Data packages hold only data and reuse the toolkit and its gates, for any standard: IEC 60617, ISO 14617, ISA 5.1 or your own.

Status: alpha. The toolkit the spec below describes is built: reading, resolving, linting, SVG and the build, with every lint rule and gate proven by a failing fixture. Published on PyPI from v0.4.0; v0.1.0 to v0.3.0 were git tags named graphical-symbols.

Every example symbol in this repository, the docs and the gallery included, is drawn independently in the style of a published standard (IEC 60617 for the S000xx numbers). None is copied from the IEC database or from any standard's own drawings. Each is marked status = "unverified": nobody has checked it against the standard.

Documentation: https://olejbondahl.github.io/symdef/ (tutorial, guide, symbol interface, API reference and a gallery).

Install

uv add symdef

or pip install symdef.

Python 3.14 or later, with no runtime dependencies.

The functions in symdef.files, symdef.project and symdef.cli read or write files, or print. Everything else is pure: the same input gives the same output, with no file I/O, clock, randomness or global state. The top-level symdef namespace re-exports both kinds. More depth: docs/GUIDE.md.

The design

src/symdef/docs/SYMBOL_INTERFACE.html is the binding, final spec. Open it in a browser; it ships as package data, readable at runtime through importlib.resources.files("symdef").joinpath("docs/SYMBOL_INTERFACE.html"). The key ideas:

• A symbol is a definition: no tag, terminal numbers, position or orientation. Those belong to the placement in a drawing library.
• Port ids are roles (in, out, anode, ...), never terminal markings (13, A1).
• Electrical function is data: nodes and typed paths, so a consumer can netlist without per-symbol knowledge.
• Text lives in slots: the symbol reserves boxes for tags and terminal markings.
• Module units (M = 2.5 mm), a 0.125 M drawing grid and a 1 M wiring grid. A strict wiring contract is linted in all 8 orientations.
• Composition mirrors the standard: composites reference parts by anchor, no copied coordinates.

What is here

The data model and orient, the boxes and repeat, the TOML reader with its JSON Schema (src/symdef/schema/symbol.schema.json), the composition resolver, 35 lint rules, plain and annotated SVG, and the build (resolved JSON per symbol, the bundle, SVGs, a gallery README). Decisions the spec leaves open, and concerns about the spec, are in docs/DECISIONS.md.

Use

A data repo has library.toml and symbols/<number>.toml; root below is its directory.

from symdef import lint, load_library
from symdef.lint import RULES

library = load_library(root)  # raises LibraryError, listing every problem in the files
contact = library.get("S00227")  # by number; iterating a library is sorted by number
assert len(RULES) == 35  # the spec's 33 rules plus lead-off-port (D40) and stretch-cut
findings = lint(contact)  # all 35 rules, geometric ones in all 8 orientations
assert findings == ()  # the spec's make contact lints clean
for finding in findings:  # each has .rule, .severity, .message, .location, .orientation
    print(finding.rule, finding.location, finding.message)

Symbols are immutable; orient, translate and repeat return new ones. A repeated symbol is an ordinary symbol with ports such as 1.in and 3.out.

from symdef import Orientation, keepout_box, orient, repeat, to_svg

breaker = orient(repeat(contact, 3), Orientation.R0)
print(keepout_box(breaker))
svg = to_svg(breaker, annotate=True, texts={"tag": "-Q1"})

write_build writes build/ and src/<package>/bundle.json under the repo; stale_build lists the files that differ from what it would write, so a test can fail when a committed build is out of date. load_bundle reads a bundle back without the sources. <package> is the standard's normalised name (lowercase letters and digits, D8): the example's standard is IEC 60617, so its package is iec60617.

from symdef import load_bundle, stale_build, write_build

write_build(library, root)
assert stale_build(library, root) == ()
assert len(load_bundle(root / "src" / "iec60617" / "bundle.json")) == len(library)

Development

uv sync
just ci        # format check, ruff, ty, vulture, purity gate, pytest with coverage

Coverage must stay at 100% (--cov-fail-under=100), so a partial run such as uv run pytest tests/test_units.py fails on coverage alone: add --no-cov for one. tests/test_readme.py runs the examples above and those in docs/GUIDE.md, so they stay true. Agents: start at AGENTS.md.

License

MIT, see LICENSE.