Next: Using Hierarchical Packages without Modifying cl:find-package, Up: Compatibility with ANSI Common Lisp [Contents][Index]
cl:find-packageUsing relative hierarchical package names requires a simple
modification of cl:find-package.
In ANSI Common Lisp, cl:find-package, if passed a package object,
returns it; if passed a string, cl:find-package looks for a
package with that string as its name or nickname, and returns the
package if it finds one, or returns nil if it does not; if passed a
symbol, the symbol name (a string) is extracted and
cl:find-package proceeds as it does with a string.
For implementing hierarchical packages, the behavior when the argument
is a package object (return it) does not change. But when the argument
is a string starting with one or more dots not directly naming a
package, cl:find-package will, instead of returning nil, check
whether the string can be resolved as naming a relative package, and
if so, return the associated absolute package object. (If the argument
is a symbol, the symbol name is extracted and cl:find-package
proceeds as it does with a string argument.)
Note that you should not use leading dots in package names when using hierarchical packages.