This page captures the shared infrastructure that keeps all regions inside $steelsnakes$ synchronized: the data caches (SectionDatabase) and the wiring layer (SectionFactory) that turns cached rows into concrete section objects.

SectionDatabase

1. Discovery & caching. When you instantiate SectionDatabase, it auto-discovers the correct data/<REGION>/ directory via several fallback paths, optionally respects an injected data_directory, and loads every supported SectionType into a dictionary cache. Metadata like _section_type and _region are added to every entry so downstream tools understand the source.
2. Fallback SQLite support. The constructor accepts use_sqlite=True, in which case _load_section_type can attempt to read from an SQLite table named after each SectionType when JSON files are absent. Error handling already logs missing tables and malformed rows without breaking the entire initialization.
3. Resilient lookup helpers. find_section first tries an exact match, then _fuzzy_find_section:
4. Exact matches ignore case and normalize separators (, -, _, ×).
5. Difflib-based similarity matching provides a controlled suggestion (cutoff 0.8) before falling back to None.
6. get_similar_sections can be called independently with n suggestions across all loaded types.
7. Criteria-based search. search_sections(section_type, prop__gt=100, prop__eq="W") filters the cached dict via comparison operators (gt, lt, gte, lte, eq, ne) and exact matches, so you can quickly find all sections that meet size thresholds.

SectionFactory

SectionFactory bridges SectionDatabase with the concrete section classes.

1. Automatic class loading. If no section_classes mapping is provided, the factory inspects database.region and imports the relevant modules (UK, EU, US, AU, NZ are wired in), while gracefully logging if a region lacks exports.
2. Region-aware wiring. Each helper (e.g., _load_UK_classes) imports the region's section definitions (beams, channels, angles, hollow sections) and maps them to SectionType members. This keeps the factory thin while letting each region evolve independently.
3. Extensibility. Custom section classes or alternative databases can simply pass their own section_classes dict when instantiating the factory, so testing helpers can swap in fake sections without touching the auto-loader.

Pair any factory instance with the database you already created to request a section instance:

from steelsnakes.base.database import SectionDatabase
from steelsnakes.base.factory import SectionFactory
from steelsnakes.base.sections import SectionType

db = SectionDatabase(region="UK")
factory = SectionFactory(database=db)
beam = factory.create_section("457x191x67", section_type=SectionType.UB)

The next page in this reference dives into the region-specific APIs for UK, EU, US, and additional locales.