shadow symbol-names &optional package => t
Arguments and Values:
symbol-names---a designator for a list of string designators.
package---a package designator. The default is the current package.
shadow assures that symbols with names given by symbol-names are present in the package.
Specifically, package is searched for symbols with the names supplied by symbol-names. For each such name, if a corresponding symbol is not present in package (directly, not by inheritance), then a corresponding symbol is created with that name, and inserted into package as an internal symbol. The corresponding symbol, whether pre-existing or newly created, is then added, if not already present, to the shadowing symbols list of package.
(package-shadowing-symbols (make-package 'temp)) => NIL (find-symbol 'car 'temp) => CAR, :INHERITED (shadow 'car 'temp) => T (find-symbol 'car 'temp) => TEMP::CAR, :INTERNAL (package-shadowing-symbols 'temp) => (TEMP::CAR)
(make-package 'test-1) => #<PACKAGE "TEST-1"> (intern "TEST" (find-package 'test-1)) => TEST-1::TEST, NIL (shadow 'test-1::test (find-package 'test-1)) => T (shadow 'TEST (find-package 'test-1)) => T (assert (not (null (member 'test-1::test (package-shadowing-symbols (find-package 'test-1)))))) (make-package 'test-2) => #<PACKAGE "TEST-2"> (intern "TEST" (find-package 'test-2)) => TEST-2::TEST, NIL (export 'test-2::test (find-package 'test-2)) => T (use-package 'test-2 (find-package 'test-1)) ;should not error
shadow changes the state of the package system in such a way that the package consistency rules do not hold across the change.
Current state of the package system.
Exceptional Situations: None.
package-shadowing-symbols, Section 11.1 (Package Concepts)
If a symbol with a name in symbol-names already exists in package, but by inheritance, the inherited symbol becomes shadowed by a newly created internal symbol.