Inspect a module origin using find_spec

importlib.util.find_spec() can expose a module's ModuleSpec without binding that module name in the current namespace. A spec includes an origin field: for source modules it is commonly a filename, while loaders without a file location can use another meaningful marker. This example looks up the standard-library sys module. In CPython, its expected origin is the exact string "built-in", so the code asserts that marker and prints the fully qualified spec name plus a deterministic Boolean result.

The concrete input is therefore "sys", not a pathname. The output does not disclose an installation directory and avoids treating origin as a universally usable filesystem path. That distinction matters: a module spec's origin describes the loader's loading location, and namespace packages may have None instead. Furthermore, module.__file__ and module.__spec__.origin are not kept synchronized if either changes at runtime. Inspect a returned spec for diagnostics or controlled routing, but do not assume that an origin alone proves provenance or that every Python implementation represents built-in modules identically.

ModuleSpec and importlib.util.find_spec() are available from Python 3.4. See the find_spec documentation and the ModuleSpec origin documentation.

import importlib.util

spec = importlib.util.find_spec("sys")

assert spec is not None
assert spec.origin == "built-in"
print(f"name: {spec.name}")
print(f"origin-is-built-in: {spec.origin == 'built-in'}")
name: sys
origin-is-built-in: True

AI-assistance disclosure: AI helped draft this explanation and example.

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