asdf:find-system

(asdf:find-system name &optional (error-p t))

Returns the system metaobject for the named system: a CLOS instance of asdf:system (or of asdf:package-inferred-system for a :class :package-inferred-system one). The instance is memoized per name — repeated calls answer the same object (eq), like real ASDF — and passing a component object back in answers it unchanged. name is a string, keyword or symbol designator (a symbol downcases, a string stays verbatim).

A name that is not registered signals an error, unless error-p is nil — then the answer is nil, the probe shape libraries use ((asdf:find-system name nil) guarding a load-system). Registered means: defined by a prior asdf:defsystem or a loaded .asd, derived as a package-inferred sub-system, or one of the built-in shim systems. find-system never searches the filesystem itself.

The component model behind the instance is real ASDF's: the classes asdf:component, asdf:child-component / asdf:parent-component, asdf:module, asdf:system, asdf:package-inferred-system, asdf:source-file, asdf:cl-source-file and asdf:static-file are real CLOS classes on every backend, so typep, typecase and defmethod specializers over them all work.

Backend support

Works on all four backends. The interpreter answers from its live system registry; a compiled program carries the registry that was spliced at compile time, so find-system knows exactly the systems the program loaded (plus every defsystem the .asds declared). A literal (asdf:system-source-directory (asdf:find-system 'lib nil)) still folds to a literal namestring at compile time, so the bundled-data-file idiom needs no runtime registry.