This library defines a CLOS-based protocol to be used by Common Lisp compilers for environment query and update. In addition, library authors can use the trucler-native interface to inspect native environments. Trucler supports introspection for variables, functions, tags, blocks and optimization policies.

The following macro can be used to ensure the presence of a local symbol macro, and to see whether it has the expected expansion:

(eval-when (:compile-toplevel :load-toplevel :execute)
  (defvar *client* (make-instance 'trucler-native:client)))

(defmacro assert-local-symbol-macro-description
    (name &key (expansion nil expansion-p) &environment env)
  (let ((description (trucler:describe-variable *client* env name)))
    (check-type description trucler:local-symbol-macro-description)
    (when expansion-p
      (assert (equal expansion (trucler:expansion description))))
    `(values)))

Trucler can also be used to inspect the runtime environment - here with an example of querying the state of the variable *print-array*.

(trucler:describe-variable
 (make-instance 'trucler-native:client)
 nil
 '*print-array*)
; => #<trucler-native-sbcl::global-special-variable-description {100A7E5A23}>

Trucler can be seen as a modern, extensible version of the protocol described in section 8.5 of the second edition of Guy Steele’s book Common Lisp, the Language.