schema2object

JSON Schema as header file. Like C's .h, like TypeScript's type system — but at runtime, cross-language, and removable.

	TypeScript	C .h	schema2object
Type definition	.ts file, erased at compile	.h file, compile-time only	JSON Schema, lives at runtime
Validation	compile-time only, runtime naked	compile-time only	construction IS validation
Cross-language	JS only	C/C++ only	JSON Schema = language-agnostic
Removable	no, build step required	no, compilation required	yes — mature code runs without it, zero overhead
Self-describing	no	no	schema is machine-readable documentation

Not a validator. Not a hint. The schema is the class — data is the instance.

JSON came from JavaScript objects. Serialization stripped the methods. schema2object restores them: bind a Draft-07 schema to a runtime object and the schema enforces itself — invalid data cannot become an instance, invalid writes cannot reach storage, and Draft-07 logic keywords become callable methods.

Use it as scaffolding: develop with full schema validation, then remove it when mature — the contracts are already baked into your code. bashjsast demonstrates this: built with schema2object, shipped as raw dict. 840x faster, zero regression.

Core Semantics

These are internal mechanisms of the class, not external validation steps:

• Instantiation enforces the schema. ObjectTree(data, schema) raises if data is not a valid instance of schema. This is not validation — it is what it means to instantiate a class.
• Assignment enforces the field contract. Writing to a field checks the field's schema before storage. The class rejects what does not fit.
• to_dict() projects the schema. Serialization returns schema-defined fields only. Extra runtime fields exist but are outside the class definition.
• Unknown fields are permitted at runtime. The instance can carry state beyond the schema, as any object can. It just does not appear in to_dict().

Draft-07 Logic → Methods

Draft-07 combinators are the class's behavioral logic, not query operations on external data:

Draft-07	JS method	Python method	Semantics
oneOf	$oneOf()	one_of()	XOR — re-bind to the single matching sub-schema
anyOf	$anyOf()	any_of()	OR — re-bind to all matching sub-schemas
allOf	$allOf()	all_of()	AND — re-bind to merged schema
not	$notOf()	not_of()	NOT — true if instance does not match
if/then/else	$ifThen()	if_then()	CASE WHEN — re-bind to the matching branch
properties	$project()	project()	SELECT — keep only schema-defined fields
contains	$contains()	contains()	EXISTS — true if any array element matches
default	$withDefaults()	with_defaults()	fill missing fields from schema defaults

JS naming convention: All ObjectTree API methods use $ prefix ($value, $schema, $toDict(), etc.). Data properties have no prefix (tree.name, tree.email). This avoids collision when schema property names match API method names.

Implementations

Language	Directory	Draft-07 suite
JavaScript	js/	922/922
Python	python/	922/922
Rust	rust/	922/922

Philosophy

See schema-driven-development for the full methodology.

License

MIT License